Chimpanzees

@article{elliot1912a1,
    author = "Elliot, D. G",
    title = "A Review of the Primates",
    year = "1912",
    journal = "New York, American Museum of Natural History",
    note = "talkorigins\_source = {true}; raw\_reference = {Elliot, D. G., 1912, A Review of the Primates: New York, American Museum of Natural History.}"
}

The relative cross-reactivities as judged by tile quantitative precipitation reaction of 22 primate serum albumins were determined with pooled antiserums against human Serum albumnini. The atitgenic correspondences to human serum albumin of all but three serum albumin fell into narrow ranges, and the groups defined by these ranges are distinct taxonomic categories. The values of the cross-reactivity ranges are consistent with the presumed phylogenetic relationships to man on the assumption that the evolutionary modification of protein structure has been progressive and divergent.

@article{doi101126science15137171530,
    author = "Hafleigh, Ann S. and Williams, Curtis A.",
    title = "Antigenic Correspondence of Serum Albumins among the Primates",
    year = "1966",
    journal = "Science",
    abstract = "The relative cross-reactivities as judged by tile quantitative precipitation reaction of 22 primate serum albumins were determined with pooled antiserums against human Serum albumnini. The atitgenic correspondences to human serum albumin of all but three serum albumin fell into narrow ranges, and the groups defined by these ranges are distinct taxonomic categories. The values of the cross-reactivity ranges are consistent with the presumed phylogenetic relationships to man on the assumption that the evolutionary modification of protein structure has been progressive and divergent.",
    url = "https://doi.org/10.1126/science.151.3717.1530",
    doi = "10.1126/science.151.3717.1530",
    openalex = "W1987485113"
}

Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans the biological, physical, and social sciences.

@article{doi101073pnas581142,
    author = "Sarich, Vincent M. and Wilson, Allan C.",
    title = "Rates of albumin evolution in primates.",
    year = "1967",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans the biological, physical, and social sciences.",
    url = "https://doi.org/10.1073/pnas.58.1.142",
    doi = "10.1073/pnas.58.1.142",
    openalex = "W2095123791",
    references = "doi101002ajpa1330220242, doi1010160003986154904750, doi1010160019279164900527, doi101111j174966321962tb13656x, doi101126science1473660836, doi101126science15137171530, doi101126science15437561563, doi101210endo773563, openalexw2417198282"
}

@article{doi101038217624a0,
    author = "KIMURA, MOTOO",
    title = "Evolutionary Rate at the Molecular Level",
    year = "1968",
    journal = "Nature",
    url = "https://doi.org/10.1038/217624a0",
    doi = "10.1038/217624a0",
    openalex = "W1993351732",
    references = "doi101001jama196603100230164053, doi101007bf02984069, doi101016b9781483227344500176, doi101093genetics16297, doi101093genetics494725, doi101093genetics542577, doi101093genetics542595, doi101098rspb19660032, doi101126science147365368, openalexw2171582839"
}

After prolonged exposure to their reflected images in mirrors, chimpanzees marked with red dye showed evidence of being able to recognize their own reflections. Monkeys did not appear to have this capacity.

@article{doi101126science167391486,
    author = "Gallup, Gordon G.",
    title = "Chimpanzees: Self-Recognition",
    year = "1970",
    journal = "Science",
    abstract = "After prolonged exposure to their reflected images in mirrors, chimpanzees marked with red dye showed evidence of being able to recognize their own reflections. Monkeys did not appear to have this capacity.",
    url = "https://doi.org/10.1126/science.167.3914.86",
    doi = "10.1126/science.167.3914.86",
    openalex = "W2092192102",
    references = "doi101016b9781483228204500147, doi101037h0026777, doi103406enfan19541469"
}

@article{doi101126science17940781144,
    author = "Sarich, Vincent M. and Wilson, Allan C.",
    title = "Generation Time and Genomic Evolution in Primates",
    year = "1973",
    journal = "Science",
    url = "https://doi.org/10.1126/science.179.4078.1144",
    doi = "10.1126/science.179.4078.1144",
    openalex = "W2092437348",
    references = "doi101007bf01659390, doi101007bf01659392, doi101007bf01659396, doi101038202147a0, doi101038224149a0, doi101073pnas581142, doi101073pnas6341088, doi101126science1553760279, doi101126science15838051200, doi101146annurevmi23100169002415, uzzell1971phyletic"
}

@article{doi101126science1090005,
    author = "King, Mary‐Claire and Wilson, Allan C.",
    title = "Evolution at Two Levels in Humans and Chimpanzees",
    year = "1975",
    journal = "Science",
    url = "https://doi.org/10.1126/science.1090005",
    doi = "10.1126/science.1090005",
    openalex = "W2128969076",
    references = "doi101007bf00485780, doi101016002228367190324x, doi101016s002192581861823x, doi1010179781316276259010, doi101038224149a0, doi101073pnas581142, doi101073pnas6341088, doi101073pnas7183028, doi101093genetics701113, doi101126science15838051200, doi1023073001850, doi1043249781315081083, sarich1967immunological"
}

@misc{king1975evolution2,
    author = "King, M. C. and Wilson, A. C",
    title = "Evolution at two levels in humans and chimpanzees",
    year = "1975",
    howpublished = "Science, v. 188, p. 107-118",
    note = "talkorigins\_source = {true}; raw\_reference = {King, M. C., and Wilson, A. C., 1975, Evolution at two levels in humans and chimpanzees: Science, v. 188, p. 107-118.}"
}

@article{doi101007bf01734101,
    author = "Brown, Wesley M. and Prager, Ellen M. and Wang, Alice and Wilson, Allan C.",
    title = "Mitochondrial DNA sequences of primates: Tempo and mode of evolution",
    year = "1982",
    journal = "Journal of Molecular Evolution",
    url = "https://doi.org/10.1007/bf01734101",
    doi = "10.1007/bf01734101",
    openalex = "W2037764264",
    references = "doi101007bf01659159, doi1010160022283682901371, doi1010160092867481903007, doi101016b9781483232119500097, doi101016s0076687980650599, doi101038290457a0, doi101073pnas7641967, doi101086282802, doi101126science1553760279, doi101126science15838051200, doi1023071441916, doi1023072987461, openalexw2601913882, sarich1967immunological"
}

Abstract The chimpanzees of the Tai National Park, Ivory Coast, use sticks and stones to open 5 different species of nuts. In spite of an unfavourable availability of the material in the forest, the animals choose their tools adaptively. For cracking harder nuts, they use harder and heavier tools and transport tools more often and from farther away. Some aspects of the evolution of tool-use in primates are discussed.

@article{doi101163156853983x00192,
    author = "Boesch, Christophe and Boesch, H.",
    title = "Optimisation of Nut-Cracking With Natural Hammers By Wild Chimpanzees",
    year = "1983",
    journal = "Behaviour",
    abstract = "Abstract The chimpanzees of the Tai National Park, Ivory Coast, use sticks and stones to open 5 different species of nuts. In spite of an unfavourable availability of the material in the forest, the animals choose their tools adaptively. For cracking harder nuts, they use harder and heavier tools and transport tools more often and from farther away. Some aspects of the evolution of tool-use in primates are discussed.",
    url = "https://doi.org/10.1163/156853983x00192",
    doi = "10.1163/156853983x00192",
    openalex = "W2073180890",
    references = "doi101002ajpa1330550202"
}

Abstract Innovative behaviour achieved through exploration, learning and insight heavily depends on certain motivational, social and ecological conditions of short duration. We propose that more attention should be given to what these conditions are and where they are realized in natural groups of non-human primates. Only to the extent that such favourable conditions were frequently realized in a social structure or an extraspecific environment could selective pressures act on innovative abilities. There is hope that research into field conditions of innovative behaviour will help to identify its selectors in evolution.

@article{doi101098rstb19850020,
    author = "Kummer, Hans and Goodall, Jane",
    title = "Conditions of innovative behaviour in primates",
    year = "1985",
    journal = "Philosophical transactions of the Royal Society of London. Series B, Biological sciences",
    abstract = "Abstract Innovative behaviour achieved through exploration, learning and insight heavily depends on certain motivational, social and ecological conditions of short duration. We propose that more attention should be given to what these conditions are and where they are realized in natural groups of non-human primates. Only to the extent that such favourable conditions were frequently realized in a social structure or an extraspecific environment could selective pressures act on innovative abilities. There is hope that research into field conditions of innovative behaviour will help to identify its selectors in evolution.",
    url = "https://doi.org/10.1098/rstb.1985.0020",
    doi = "10.1098/rstb.1985.0020",
    openalex = "W2109105580"
}

Presents a scientific chronicle of Jane Goodall's career and documents the Gombe chimpanzees social behavior over the last 26 years.

@book{openalexw2001431842,
    author = "Goodall, Jane",
    title = "The Chimpanzees of Gombe: Patterns of Behavior",
    year = "1986",
    abstract = "Presents a scientific chronicle of Jane Goodall's career and documents the Gombe chimpanzees social behavior over the last 26 years.",
    url = "https://openalex.org/W2001431842",
    openalex = "W2001431842"
}

Hunting is often considered one of the major behaviors that shaped early hominids' evolution, along with the shift toward a drier and more open habitat. We suggest that a precise comparison of the hunting behavior of a species closely related to man might help us understand which aspects of hunting could be affected by environmental conditions. The hunting behavior of wild chimpanzees is discussed, and new observations on a population living in the tropical rain forest of the Taï National Park, Ivory Coast, are presented. Some of the forest chimpanzees' hunting performances are similar to those of savanna-woodlands populations; others are different. Forest chimpanzees have a more specialized prey image, intentionally search for more adult prey, and hunt in larger groups and with a more elaborate cooperative level than savanna-woodlands chimpanzees. In addition, forest chimpanzees tend to share meat more actively and more frequently. These findings are related to some theories on aspects of hunting behavior in early hominids and discussed in order to understand some factors influencing the hunting behavior of wild chimpanzees. Finally, the hunting behavior of primates is compared with that of social carnivores.

@article{doi101002ajpa1330780410,
    author = "Boesch, Christophe and Boesch, H.",
    title = "Hunting behavior of wild chimpanzees in the Taï National Park",
    year = "1989",
    journal = "American Journal of Physical Anthropology",
    abstract = "Hunting is often considered one of the major behaviors that shaped early hominids' evolution, along with the shift toward a drier and more open habitat. We suggest that a precise comparison of the hunting behavior of a species closely related to man might help us understand which aspects of hunting could be affected by environmental conditions. The hunting behavior of wild chimpanzees is discussed, and new observations on a population living in the tropical rain forest of the Taï National Park, Ivory Coast, are presented. Some of the forest chimpanzees' hunting performances are similar to those of savanna-woodlands populations; others are different. Forest chimpanzees have a more specialized prey image, intentionally search for more adult prey, and hunt in larger groups and with a more elaborate cooperative level than savanna-woodlands chimpanzees. In addition, forest chimpanzees tend to share meat more actively and more frequently. These findings are related to some theories on aspects of hunting behavior in early hominids and discussed in order to understand some factors influencing the hunting behavior of wild chimpanzees. Finally, the hunting behavior of primates is compared with that of social carnivores.",
    url = "https://doi.org/10.1002/ajpa.1330780410",
    doi = "10.1002/ajpa.1330780410",
    openalex = "W1984441627",
    references = "doi101007978146847862422, doi1010160022519364900384, doi101038scientificamerican096062, doi1010970000505319570700000032, doi101126science7466396, doi101525aa198688102a00020, doi1023071296618, doi1023072260026, doi1023072798801, doi1023073498751, doi104324978131512740848, openalexw2001431842, openalexw2126603167"
}

Examining the pattern of nucleotide substitution for the control region of mitochondrial DNA (mtDNA) in humans and chimpanzees, we developed a new mathematical method for estimating the number of transitional and transversional substitutions per site, as well as the total number of nucleotide substitutions. In this method, excess transitions, unequal nucleotide frequencies, and variation of substitution rate among different sites are all taken into account. Application of this method to human and chimpanzee data suggested that the transition/transversion ratio for the entire control region was approximately 15 and nearly the same for the two species. The 95% confidence interval of the age of the common ancestral mtDNA was estimated to be 80,000-480,000 years in humans and 0.57-2.72 Myr in common chimpanzees.

@article{doi101093oxfordjournalsmolbeva040023,
    author = "Tamura, Koichiro and Nei, M",
    title = "Estimation of the number of nucleotide substitutions in the control region of mitochondrial DNA in humans and chimpanzees.",
    year = "1993",
    journal = "Molecular Biology and Evolution",
    abstract = "Examining the pattern of nucleotide substitution for the control region of mitochondrial DNA (mtDNA) in humans and chimpanzees, we developed a new mathematical method for estimating the number of transitional and transversional substitutions per site, as well as the total number of nucleotide substitutions. In this method, excess transitions, unequal nucleotide frequencies, and variation of substitution rate among different sites are all taken into account. Application of this method to human and chimpanzee data suggested that the transition/transversion ratio for the entire control region was approximately 15 and nearly the same for the two species. The 95\% confidence interval of the age of the common ancestral mtDNA was estimated to be 80,000-480,000 years in humans and 0.57-2.72 Myr in common chimpanzees.",
    url = "https://doi.org/10.1093/oxfordjournals.molbev.a040023",
    doi = "10.1093/oxfordjournals.molbev.a040023",
    openalex = "W2144775551",
    references = "doi101007bf01731581, doi101007bf01734101, doi101007bf02101694, doi101093genetics1052437, doi101093oxfordjournalsmolbeva040410, doi101093oxfordjournalsmolbeva040454, doi101093oxfordjournalsmolbeva040752, doi101093oxfordjournalsmolbeva040771, doi101126science1840702, doi1023073213548"
}

The last decade has seen a resurgence of interest in laterality of function in primates, especially in hand use as it links to handedness and language in Homo sapiens. Manual lateralization of behavior in humans reflects asymmetry in cerebral structure, which must have evolved from nonhuman progenitors. To what extent is hand function lateralized in our nearest living relations? First, we address current issues of theory and methodology: statistics, measurement, variables, setting, sensory modality, and sample size. Specific topics include preference vs. performance, posture, bimanuality, inheritance, and arm asymmetry. We categorize the published literature in a descriptive, classificatory framework of five levels that range from Level 1, ambilaterality, to Level 5, human-like handedness. In a meta-analysis we put 241 published data-sets to a methodological test of seven criteria and code the 48 survivors onto the levels framework, by taxonomic grouping (prosimian, New World monkey, Old World monkey, ape, chimpanzee). Primates at Level 1 are mostly wild or naturalistic populations performing spontaneous species-typical behavior patterns. Most primates are at Levels 2 and 3, that is, individually lateralized to either side, especially on complex, demanding or practiced tasks, usually as devised in captive settings. Only chimpanzees show signs of population-level bias (Levels 4 and 5) to the right, but only in captivity and only incompletely. We conclude that nonhuman primate hand function has not been shown to be lateralized at the species level—it is not the norm for any species, task, or setting, and so offers no easy model for the evolution of human handedness. Yrbk Phys Anthropol 40:201–232, 1997. © 1997 Wiley-Liss, Inc.

@article{doi101002sici10968644199725201aidajpa830co26,
    author = "McGrew, William C. and Marchant, Linda F.",
    title = "On the other hand: Current issues in and meta-analysis of the behavioral laterality of hand function in nonhuman primates",
    year = "1997",
    journal = "American Journal of Physical Anthropology",
    abstract = "The last decade has seen a resurgence of interest in laterality of function in primates, especially in hand use as it links to handedness and language in Homo sapiens. Manual lateralization of behavior in humans reflects asymmetry in cerebral structure, which must have evolved from nonhuman progenitors. To what extent is hand function lateralized in our nearest living relations? First, we address current issues of theory and methodology: statistics, measurement, variables, setting, sensory modality, and sample size. Specific topics include preference vs. performance, posture, bimanuality, inheritance, and arm asymmetry. We categorize the published literature in a descriptive, classificatory framework of five levels that range from Level 1, ambilaterality, to Level 5, human-like handedness. In a meta-analysis we put 241 published data-sets to a methodological test of seven criteria and code the 48 survivors onto the levels framework, by taxonomic grouping (prosimian, New World monkey, Old World monkey, ape, chimpanzee). Primates at Level 1 are mostly wild or naturalistic populations performing spontaneous species-typical behavior patterns. Most primates are at Levels 2 and 3, that is, individually lateralized to either side, especially on complex, demanding or practiced tasks, usually as devised in captive settings. Only chimpanzees show signs of population-level bias (Levels 4 and 5) to the right, but only in captivity and only incompletely. We conclude that nonhuman primate hand function has not been shown to be lateralized at the species level—it is not the norm for any species, task, or setting, and so offers no easy model for the evolution of human handedness. Yrbk Phys Anthropol 40:201–232, 1997. © 1997 Wiley-Liss, Inc.",
    url = "https://doi.org/10.1002/(sici)1096-8644(1997)25+<201::aid-ajpa8>3.0.co;2-6",
    doi = "10.1002/(sici)1096-8644(1997)25+<201::aid-ajpa8>3.0.co;2-6",
    openalex = "W2014689971",
    references = "doi1010160016003257907664, doi101016s0003347274800540, doi101017cbo9781139168342, doi101017s0140525x00047695, doi101111j155856461962tb03206x, doi101192bjp1305421, doi1023073498751, doi1023075248, openalexw1591640611, openalexw595961698"
}

@article{doi10103821415,
    author = "Whiten, Andrew and Goodall, J. and McGrew, William C. and Nishida, Toshisada and Reynolds, Vernon and Sugiyama, Yukimaru and Tutin, Caroline E. G. and Wrangham, Richard W. and Boesch, Christophe",
    title = "Cultures in chimpanzees",
    year = "1999",
    journal = "Nature",
    url = "https://doi.org/10.1038/21415",
    doi = "10.1038/21415",
    openalex = "W1795671969",
    references = "doi101007bf02692251, doi101016s0065345408601461, doi101017cbo9780511565519, doi101017s0140525x0003123x, doi1043249781315801889, doi105860choice310304, doi105860choice332735, openalexw1482083705, openalexw1968932337, openalexw2001431842"
}

@article{doi101023a1012065332758,
    author = "Ross, Caroline",
    title = "Park or Ride? Evolution of Infant Carrying in Primates",
    year = "2001",
    journal = "International Journal of Primatology",
    url = "https://doi.org/10.1023/a:1012065332758",
    doi = "10.1023/a:1012065332758",
    openalex = "W100232805"
}

Abstract Cultural variation among chimpanzee communities or unit-groups at nine long-term study sites was charted through a systematic, collaborative procedure in which the directors of the sites first agreed a candidate list of 65 behaviour patterns (here fully defined), then classified each pattern in relation to its local frequency of occurrence. Thirty-nine of the candidate behaviour patterns were discriminated as cultural variants, sufficiently frequent at one or more sites to be consistent with social transmission, yet absent at one or more others where environmental explanations were rejected. Each community exhibited a unique and substantial profile of such variants, far exceeding cultural variation reported before for any other non-human species. Evaluation of these pan-African distributions against three models for the diffusion of traditions identified multiple cases consistent with cultural evolution involving differentiation in form, function and targets of behaviour patterns.

@article{doi101163156853901317367717,
    author = "Whiten and Goodall and McGrew, William C. and Nishida and Reynolds and Sugiyama and Tutin, Caroline E. G. and Wrangham, Richard W. and Boesch",
    title = "CHARTING CULTURAL VARIATION IN CHIMPANZEES",
    year = "2001",
    journal = "Behaviour",
    abstract = "Abstract Cultural variation among chimpanzee communities or unit-groups at nine long-term study sites was charted through a systematic, collaborative procedure in which the directors of the sites first agreed a candidate list of 65 behaviour patterns (here fully defined), then classified each pattern in relation to its local frequency of occurrence. Thirty-nine of the candidate behaviour patterns were discriminated as cultural variants, sufficiently frequent at one or more sites to be consistent with social transmission, yet absent at one or more others where environmental explanations were rejected. Each community exhibited a unique and substantial profile of such variants, far exceeding cultural variation reported before for any other non-human species. Evaluation of these pan-African distributions against three models for the diffusion of traditions identified multiple cases consistent with cultural evolution involving differentiation in form, function and targets of behaviour patterns.",
    url = "https://doi.org/10.1163/156853901317367717",
    doi = "10.1163/156853901317367717",
    openalex = "W2131092692",
    references = "doi101159000156428"
}

Despite considerable current interest in the evolution of intelligence, the intuitively appealing notion that brain volume and "intelligence" are linked remains untested. Here, we use ecologically relevant measures of cognitive ability, the reported incidence of behavioral innovation, social learning, and tool use, to show that brain size and cognitive capacity are indeed correlated. A comparative analysis of 533 instances of innovation, 445 observations of social learning, and 607 episodes of tool use established that social learning, innovation, and tool use frequencies are positively correlated with species' relative and absolute "executive" brain volumes, after controlling for phylogeny and research effort. Moreover, innovation and social learning frequencies covary across species, in conflict with the view that there is an evolutionary tradeoff between reliance on individual experience and social cues. These findings provide an empirical link between behavioral innovation, social learning capacities, and brain size in mammals. The ability to learn from others, invent new behaviors, and use tools may have played pivotal roles in primate brain evolution.

@article{doi101073pnas062041299,
    author = "Reader, Simon M. and Laland, Kevin N.",
    title = "Social intelligence, innovation, and enhanced brain size in primates",
    year = "2002",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = {Despite considerable current interest in the evolution of intelligence, the intuitively appealing notion that brain volume and "intelligence" are linked remains untested. Here, we use ecologically relevant measures of cognitive ability, the reported incidence of behavioral innovation, social learning, and tool use, to show that brain size and cognitive capacity are indeed correlated. A comparative analysis of 533 instances of innovation, 445 observations of social learning, and 607 episodes of tool use established that social learning, innovation, and tool use frequencies are positively correlated with species' relative and absolute "executive" brain volumes, after controlling for phylogeny and research effort. Moreover, innovation and social learning frequencies covary across species, in conflict with the view that there is an evolutionary tradeoff between reliance on individual experience and social cues. These findings provide an empirical link between behavioral innovation, social learning capacities, and brain size in mammals. The ability to learn from others, invent new behaviors, and use tools may have played pivotal roles in primate brain evolution.},
    url = "https://doi.org/10.1073/pnas.062041299",
    doi = "10.1073/pnas.062041299",
    openalex = "W2156834836",
    references = "doi101016s0047248477801358, doi10103844766, doi101093bioinformatics113247, doi101093oso97801951062370010001, doi101093oso97801985464120010001, doi101126science7777856, doi1023071367778, doi1023075248, doi105860choice295104, doi105860choice352112, openalexw1482083705, openalexw79275703"
}

Demography provides critical data to increase our understanding of the evolution, ecology, and conservation of primate populations. The chimpanzees of the Mahale Mountains National Park, Tanzania, have been studied for more than 34 yr on the basis of individual identification and standardized attendance records. From this long-term study, we derived the following demographic data: The major cause of death was disease (48%), followed by senescence (24%) and within-species aggression (16%). Fifty percent of Mahale chimpanzees died before weaning. The median ages of female life history variables were: first maximal swelling, 10.0 yr (n = 5); emigration, 11.0 yr (n = 11); and first birth, 13.1 yr (n = 5). The median period of adolescent infertility was 2.8 yr (n = 4) when calculated from the age at immigration to that at first birth. Female fecundity was highest between 20 and 35 yr of age, with an annual birth rate of 0.2. Twenty-six females that were observed from a young age (10-13 yr) to death at various ages (15-40 yr) gave birth to an average of 3.9 and weaned an average of 1.4 offspring. Twenty-five females that were observed from middle age (18-33 yr) to death in older age (31-48) gave birth to an average of 2.7 and weaned an average of 2.0 offspring. The post-reproductive lifespan for female chimpanzees was defined as the number of years that passed from the year when the last offspring was born to the year when the female died, minus 5. Twenty-five percent of old females had a post-reproductive lifespan. The interbirth interval after the birth of a son (x = 72 mo) tended to be longer than that after the birth of a daughter (x = 66 mo). The extent of female transfer, which is a rule in chimpanzees, is influenced by the size and composition of the unit group and size of the overall local community.

@article{doi101002ajp10068,
    author = "Nishida, Toshisada and Hamai, Miya and Hasegawa, Toshikazu and Hiraiwa‐Hasegawa, Mariko and Hosaka, Kazuhiko and Hunt, Kevin D. and Itoh, Noriko and Kawanaka, Kenji and Matsumoto–Oda, Akiko and Mitani, John C. and Nakamura, Michio and Norikoshi, Koshi and Sakamaki, Tetsuya and Turner, Linda A. and Uehara, Shigeo and Zamma, Koichiro",
    title = "Demography, female life history, and reproductive profiles among the chimpanzees of Mahale",
    year = "2003",
    journal = "American Journal of Primatology",
    abstract = "Demography provides critical data to increase our understanding of the evolution, ecology, and conservation of primate populations. The chimpanzees of the Mahale Mountains National Park, Tanzania, have been studied for more than 34 yr on the basis of individual identification and standardized attendance records. From this long-term study, we derived the following demographic data: The major cause of death was disease (48\%), followed by senescence (24\%) and within-species aggression (16\%). Fifty percent of Mahale chimpanzees died before weaning. The median ages of female life history variables were: first maximal swelling, 10.0 yr (n = 5); emigration, 11.0 yr (n = 11); and first birth, 13.1 yr (n = 5). The median period of adolescent infertility was 2.8 yr (n = 4) when calculated from the age at immigration to that at first birth. Female fecundity was highest between 20 and 35 yr of age, with an annual birth rate of 0.2. Twenty-six females that were observed from a young age (10-13 yr) to death at various ages (15-40 yr) gave birth to an average of 3.9 and weaned an average of 1.4 offspring. Twenty-five females that were observed from middle age (18-33 yr) to death in older age (31-48) gave birth to an average of 2.7 and weaned an average of 2.0 offspring. The post-reproductive lifespan for female chimpanzees was defined as the number of years that passed from the year when the last offspring was born to the year when the female died, minus 5. Twenty-five percent of old females had a post-reproductive lifespan. The interbirth interval after the birth of a son (x = 72 mo) tended to be longer than that after the birth of a daughter (x = 66 mo). The extent of female transfer, which is a rule in chimpanzees, is influenced by the size and composition of the unit group and size of the overall local community.",
    url = "https://doi.org/10.1002/ajp.10068",
    doi = "10.1002/ajp.10068",
    openalex = "W2151635627"
}

Several comparative research programs have focused on the cognitive, life history and ecological traits that account for variation in brain size. We review one of these programs, a program that uses the reported frequency of behavioral innovation as an operational measure of cognition. In both birds and primates, innovation rate is positively correlated with the relative size of association areas in the brain, the hyperstriatum ventrale and neostriatum in birds and the isocortex and striatum in primates. Innovation rate is also positively correlated with the taxonomic distribution of tool use, as well as interspecific differences in learning. Some features of cognition have thus evolved in a remarkably similar way in primates and at least six phyletically-independent avian lineages. In birds, innovation rate is associated with the ability of species to deal with seasonal changes in the environment and to establish themselves in new regions, and it also appears to be related to the rate at which lineages diversify. Innovation rate provides a useful tool to quantify inter-taxon differences in cognition and to test classic hypotheses regarding the evolution of the brain.

@article{doi101159000076784,
    author = "Lefebvre, Louis and Reader, Simon M. and Sol, Daniel",
    title = "Brains, Innovations and Evolution in Birds and Primates",
    year = "2004",
    journal = "Brain Behavior and Evolution",
    abstract = "Several comparative research programs have focused on the cognitive, life history and ecological traits that account for variation in brain size. We review one of these programs, a program that uses the reported frequency of behavioral innovation as an operational measure of cognition. In both birds and primates, innovation rate is positively correlated with the relative size of association areas in the brain, the hyperstriatum ventrale and neostriatum in birds and the isocortex and striatum in primates. Innovation rate is also positively correlated with the taxonomic distribution of tool use, as well as interspecific differences in learning. Some features of cognition have thus evolved in a remarkably similar way in primates and at least six phyletically-independent avian lineages. In birds, innovation rate is associated with the ability of species to deal with seasonal changes in the environment and to establish themselves in new regions, and it also appears to be related to the rate at which lineages diversify. Innovation rate provides a useful tool to quantify inter-taxon differences in cognition and to test classic hypotheses regarding the evolution of the brain.",
    url = "https://doi.org/10.1159/000076784",
    doi = "10.1159/000076784",
    openalex = "W2112831044",
    references = "doi101073pnas87166349, doi1023075248, doi1043249781315801889, openalexw563887495"
}

Emerging knowledge about organismal evolution suggests that changes in the regulation of gene expression have played a major role - a thesis proposed 30 years ago by King and Wilson.

@article{doi101371journalpbio0030245,
    author = "Carroll, Sean B.",
    title = "Evolution at Two Levels: On Genes and Form",
    year = "2005",
    journal = "PLoS Biology",
    abstract = "Emerging knowledge about organismal evolution suggests that changes in the regulation of gene expression have played a major role - a thesis proposed 30 years ago by King and Wilson.",
    url = "https://doi.org/10.1371/journal.pbio.0030245",
    doi = "10.1371/journal.pbio.0030245",
    openalex = "W1999027354",
    references = "doi1010079783642866593, doi101016b9781483227344500176, doi101016s0022283661800727, doi10103835046017, doi10103835097076, doi101038376479a0, doi101038nature01025, doi101038nature01262, doi101073pnas6341181, doi101073pnas7183028, doi101073pnas9794530, doi101111j001438202000tb00544x, doi101126science1090005, doi101126science1653891349, doi101126science29054941151, doi101126science860134, doi105860choice395182"
}

Human beings routinely help others to achieve their goals, even when the helper receives no immediate benefit and the person helped is a stranger. Such altruistic behaviors (toward non-kin) are extremely rare evolutionarily, with some theorists even proposing that they are uniquely human. Here we show that human children as young as 18 months of age (prelinguistic or just-linguistic) quite readily help others to achieve their goals in a variety of different situations. This requires both an understanding of others' goals and an altruistic motivation to help. In addition, we demonstrate similar though less robust skills and motivations in three young chimpanzees.

@article{doi101126science1121448,
    author = "Warneken, Felix and Tomasello, Michael",
    title = "Altruistic Helping in Human Infants and Young Chimpanzees",
    year = "2006",
    journal = "Science",
    abstract = "Human beings routinely help others to achieve their goals, even when the helper receives no immediate benefit and the person helped is a stranger. Such altruistic behaviors (toward non-kin) are extremely rare evolutionarily, with some theorists even proposing that they are uniquely human. Here we show that human children as young as 18 months of age (prelinguistic or just-linguistic) quite readily help others to achieve their goals in a variety of different situations. This requires both an understanding of others' goals and an altruistic motivation to help. In addition, we demonstrate similar though less robust skills and motivations in three young chimpanzees.",
    url = "https://doi.org/10.1126/science.1121448",
    doi = "10.1126/science.1121448",
    openalex = "W2026567452",
    references = "doi101016jtics200312003, doi101017cbo9780511805851, doi101017s0140525x02000018, doi10103700121649281126, doi101038nature04243, doi101111j146786241979tb04112x, doi1023071129406, doi1023073089337, doi1043249780203700976, doi107208chicago97802267121300010001"
}

Wild primates can become disabled due to congenital disabilities, illness, or injuries from falls and traps. Given their substantial behavioral flexibility, individuals are often able to adapt locomotion and foraging techniques to their needs, but likely incur increased energetic costs. For disabled primate mothers, the combination of altered locomotion, lactation, and infant carrying could pose a substantial energetic challenge that requires specific accommodation. Here, we describe the postural modifications for infant carrying used by five eastern chimpanzee (Pan troglodytes schweinfurthii) mothers with significant limb disabilities caused by snare injuries and compare their technique to non-disabled mothers in the same community. We describe shifts in ventral and dorsal infant carry location, as well as additional support provided to infants. Disabled mothers had altered preferences towards specific infant carrying styles and positions, and novel carrying positions not seen in non-disabled mothers. We suggest disabled chimpanzee mothers use postural adaptations to mitigate the energetic costs of infant carrying while disabled, shifting their infants' weight to an individually specific position. We discuss the plasticity of infant carrying, with individual variation present in both disabled and non-disabled mothers. We highlight that this plasticity is not unlimited, and that certain types of limb disability appear to have a substantial impact on reproductive success.

@article{doi101002ajp70152,
    author = "Péter, Hella and Akankwasa, John Walter and Kizza, Vicent and Zuberbühler, Klaus and Hobaiter, Catherine",
    title = "Postural Infant Carrying Adaptations by Wild Eastern Chimpanzees (Pan troglodytes schweinfurthii) With Limb Disabilities.",
    year = "2026",
    journal = "American journal of primatology",
    abstract = "Wild primates can become disabled due to congenital disabilities, illness, or injuries from falls and traps. Given their substantial behavioral flexibility, individuals are often able to adapt locomotion and foraging techniques to their needs, but likely incur increased energetic costs. For disabled primate mothers, the combination of altered locomotion, lactation, and infant carrying could pose a substantial energetic challenge that requires specific accommodation. Here, we describe the postural modifications for infant carrying used by five eastern chimpanzee (Pan troglodytes schweinfurthii) mothers with significant limb disabilities caused by snare injuries and compare their technique to non-disabled mothers in the same community. We describe shifts in ventral and dorsal infant carry location, as well as additional support provided to infants. Disabled mothers had altered preferences towards specific infant carrying styles and positions, and novel carrying positions not seen in non-disabled mothers. We suggest disabled chimpanzee mothers use postural adaptations to mitigate the energetic costs of infant carrying while disabled, shifting their infants' weight to an individually specific position. We discuss the plasticity of infant carrying, with individual variation present in both disabled and non-disabled mothers. We highlight that this plasticity is not unlimited, and that certain types of limb disability appear to have a substantial impact on reproductive success.",
    url = "https://pubmed.ncbi.nlm.nih.gov/41978935/",
    doi = "10.1002/ajp.70152",
    openalex = "W7154254825",
    pmid = "41978935",
    references = "doi101002ajp10068, doi101007978364222514718, doi101016jijpp201102003, doi101016s0066185668800032, doi101023a1012065332758, doi101038337260a0, doi101073pnas0508377102, doi101093acprofoso97801985154630010001, doi101098rstb19850020, doi1023072256760"
}

There has been significant research on cortical reorganization in human evolution, but much less is known about the reorganization of subcortical circuits, key partners of the cortex. Here, using advanced image analysis and comparative neuroimaging, we systematically map organizational differences in striatal, pallidal, and thalamic anatomy between humans and chimpanzees. We relate interspecies differences-proxies for evolutionary change-to genetics and behavioral correlates in humans. We show highly heritable morphological measures are expanded across species, contrasting previous cortical findings. Multivariate techniques identified morphological-cognitive latent variables linked to striatal expansion and affective variables specifically associated with conserved thalamic and pallidal regions. Our results confirm that regions tied to higher-order cognitive functions are expanded in humans, whereas regions linked to lower-order limbic functions are conserved. These findings provide new insights into subcortical architecture. Additionally, we developed tools to map neuroimaging data across species, a prerequisite for quantitatively translating animal neuroanatomy to humans.

@article{doi101038s42003026100666,
    author = "Blostein, Nadia and Devenyi, Gabriel A and Patel, Sejal and Patel, Raihaan and Tullo, Stephanie and Plitman, Eric and Costantino, Manuela and Markello, Ross and Parent, Olivier and Bedford, Saashi A and Sherwood, Chet C and Hopkins, William D and Dai, Alyssa and Seidlitz, Jakob and Raznahan, Armin and Chakravarty, M Mallar",
    title = "Morphological and anatomical variations in subcortical anatomy between humans and chimpanzees associated with heritability patterns related to human behavioral traits.",
    year = "2026",
    journal = "Communications biology",
    abstract = "There has been significant research on cortical reorganization in human evolution, but much less is known about the reorganization of subcortical circuits, key partners of the cortex. Here, using advanced image analysis and comparative neuroimaging, we systematically map organizational differences in striatal, pallidal, and thalamic anatomy between humans and chimpanzees. We relate interspecies differences-proxies for evolutionary change-to genetics and behavioral correlates in humans. We show highly heritable morphological measures are expanded across species, contrasting previous cortical findings. Multivariate techniques identified morphological-cognitive latent variables linked to striatal expansion and affective variables specifically associated with conserved thalamic and pallidal regions. Our results confirm that regions tied to higher-order cognitive functions are expanded in humans, whereas regions linked to lower-order limbic functions are conserved. These findings provide new insights into subcortical architecture. Additionally, we developed tools to map neuroimaging data across species, a prerequisite for quantitatively translating animal neuroanatomy to humans.",
    url = "https://pubmed.ncbi.nlm.nih.gov/42014585/",
    doi = "10.1038/s42003-026-10066-6",
    openalex = "W7155102164",
    pmid = "42014585",
    references = "doi101001archneurpsyc193702260220069003, doi101016jneuroimage201304127, doi101016jneuroimage201305041, doi101016s0165017399000405, doi10103879871, doi101056nejm198804073181402, doi1010970000507219851100000003, doi101109tmi20102046908, doi101146annurevne09030186002041, doi103758bf03196323"
}