African Ancestor Research Articles

A new ape from Türkiye and the radiation of late Miocene hominines

Fossil apes from the eastern Mediterranean are central to the debate on African ape and human (hominine) origins. Current research places them either as hominines, as hominins (humans and our fossil relatives) or as stem hominids, no more closely related to hominines than to pongines (orangutans and their fossil relatives). Here we show, based on our analysis of a newly identified genus, Anadoluvius, from the 8.7 Ma site of Çorakyerler in central Anatolia, that Mediterranean fossil apes are diverse, and are part of the first known radiation of early members of the hominines. The members of this radiation are currently only identified in Europe and Anatolia; generally accepted hominins are only found in Africa from the late Miocene until the Pleistocene. Hominines may have originated in Eurasia during the late Miocene, or they may have dispersed into Eurasia from an unknown African ancestor. The diversity of hominines in Eurasia suggests an in situ origin but does not exclude a dispersal hypothesis.

African mitochondrial haplogroup L7: a 100,000-year-old maternal human lineage discovered through reassessment and new sequencing

Archaeological and genomic evidence suggest that modern Homo sapiens have roamed the planet for some 300–500 thousand years. In contrast, global human mitochondrial (mtDNA) diversity coalesces to one African female ancestor (“Mitochondrial Eve”) some 145 thousand years ago, owing to the ¼ gene pool size of our matrilineally inherited haploid genome. Therefore, most of human prehistory was spent in Africa where early ancestors of Southern African Khoisan and Central African rainforest hunter-gatherers (RFHGs) segregated into smaller groups. Their subdivisions followed climatic oscillations, new modes of subsistence, local adaptations, and cultural-linguistic differences, all prior to their exodus out of Africa. Seven African mtDNA haplogroups (L0–L6) traditionally captured this ancient structure—these L haplogroups have formed the backbone of the mtDNA tree for nearly two decades. Here we describe L7, an eighth haplogroup that we estimate to be ~ 100 thousand years old and which has been previously misclassified in the literature. In addition, L7 has a phylogenetic sublineage L7a*, the oldest singleton branch in the human mtDNA tree (~ 80 thousand years). We found that L7 and its sister group L5 are both low-frequency relics centered around East Africa, but in different populations (L7: Sandawe; L5: Mbuti). Although three small subclades of African foragers hint at the population origins of L5'7, the majority of subclades are divided into Afro-Asiatic and eastern Bantu groups, indicative of more recent admixture. A regular re-estimation of the entire mtDNA haplotype tree is needed to ensure correct cladistic placement of new samples in the future.

Racial Passing off the Record: A Journey in Reconnection and Navigating Shifting Identities

Anyone of African descent or with African ancestry who engages in a genealogy project soon learns that the U.S. Census is a helpful yet frustrating tool. In 2016, equipped with my history degree and an online ancestry search engine, I searched for my great-grandfather Leroy in census records after I saw a picture of him as a young man at work in Philadelphia. This image would have been unremarkable had it not been for the fact that my African American ancestor was so light skinned that he seemed to blend in with his co-workers at Kramer’s Fruit and Vegetables. I thought there had to be a story behind this. Classified as, “Mu”, for mulatto in most of his records, Leroy became “Black” on the census in 1930. My first thought was to question whether this categorization changed for other folks like him. My research led me to my master’s thesis “From ‘Mulatto’ to ‘Negro’: How Fears of ‘Passing’ Changed the 1930 United States Census”. Through this research, I also became closer to my father’s family. This piece will take you through this journey of discovery and my frustrations along the way.

“My Uncle's Cousin's Great-Grandma Were a Cherokee” and I am Descended from an Ashanti King: The American Blood Idiom in the Simple Stories

Abstract Langston Hughes satirizes America's obsession with so-called “racial purity” in his stories featuring Jesse B. Semple to shed light upon internalized racism and white American attempts to erase US histories that complicate the standardized black-white color line. In his poem “The Negro Speaks of Rivers” (1920), the speaker challenges a singular view of the many Black histories that exist through the metaphor of rivers. In his Simple stories, Hughes's character Jesse B. Semple reflects on American Blackness and blood stereotypes that impact racial identity formation and community building. By invoking the “Indian grandmother” and royal African ancestor tropes, Hughes complicates those compartmentalized identities and US histories implied via the American blood idiom to denote associations with enslavement that bolster notions of intraracial difference and white supremacist ideology. Hughes's Simple stories culminate his trajectory in establishing African American pride in African ancestry and an anticolonial rejection of racial purity as a legal and social principle that contributes to monolithic conceptions of American Blackness.

A Review of the Antlion Fauna (Neuroptera, Myrmeleontidae) of Madagascar and Analysis of Its Genesis Based on the Collection of the Zoological Institute RAS, St. Petersburg

Based on the ZIN collection (17 species) and published data, the fauna of antlions of Madagascar is described and its origin is analyzed. An insignificant, the most ancient part of the island’s modern fauna originates from the Gondwanan fauna and characterizes Madagascar as its Cretaceous refugium. Other species or their ancestors crossed water barriers by air or water; this “feng-shui” process of Madagascar colonization with monsoons and tsunamis still continues now. Most species of the genera Centroclisis Navas, 1909, Cymothales Gerstaecker, 1894, Neuroleon Navas, 1909, Creoleon Tillyard, 1918, Myrmeleon Linnaeus, 1767, and Cueta Navas, 1911 recorded from Madagascar are common with the African continent, mainly with East Africa. The repeated ancient and recent penetration of African species to Madagascar sometimes led to isolation of taxa and subsequent speciation. The Madagascan endemics Palpares insularis McLachlan, 1894 and P. amitinus Kolbe, 1906 probably originated from a single African ancestor from the Palpares insularis–tristis group, which reached Madagascar in the Neogene. A similar way of origin can be hypothesized for other endemic species of the genus Palpares and for members of the Centroclisis maillardi (McLachlan, 1873) group, including several similar species, which must have separated from the panAfrican Centroclisis distincta (Rambur, 1842). The modern Madagascan subendemics also include the monotypic genus Neguitus Navas, 1912, close to Neuroleon, with the autochthonous species Neguitus calcaratus Navas, which probably arose in the Oligocene–Holocene on the island and later spread onto the continent with storms. The largest representatives of the endemic Gondwanan fauna, Macroleon validus (McLachlan, 1894), Crambomorphus grandidieri Weele, 1907b, and Palparellus voeltzkowi (Kolbe, 1906), the latter belonging to the endemic subgenus Palpagretus subgen. n., have a more ancient, Cretaceous–Paleocene Gondwanan origin, and their gigantism is considered a plesiomorphic feature. A Gondwanan origin is also assumed for the monotypic tribe Voltorini with the genus Voltor Navas. The endemic monotypic genus Lybekius Navas probably originated from the ancestral lineage of the tribe Pseudoformicaleontini in East Gondwana. The Oriental connections of the Madagascan endemics are less obvious, but the origin of the endemic genera Madagascarleon Fraser, 1951 and Doblina Navas, 1927 is associated with the breakup of the East Gondwana and Indigascar plates in the Cretaceous. The Madagascan endemic Paraglenurus pinnula (Auber, 1955) and the Indonesian P. scopifer (Gerstaecker, 1888) probably descended from the Oriental ancestor of numerous species on East Gondwana before the separation of Indigascar. The endemic species Pseudoformicaleo olsoufieffi (Navas, 1934) also has Australo-Oriental connections. The monotypic subgenus Palpagretus Krivokhatsky, subgen. n. is erected in Palparellus for Palparellus voeltzkowi (Kolbe, 1906). A new synonymy is established: Syngenes maritimus (Needham, 1913) = S. dolichocercus Navas, 1914, syn. n. Two color morphs are distinguished: Syngenes maritimus morpha typica with melanized spots on the CuA-anastomoses on the forewings, and S. maritimus morpha dolichocercus Navas without such spots. New combinations are formed: Centroclisis rixosa (Navas, 1912), comb. n. (ex Sogra) and Macroleon madagascariensis (Weele, 1908), comb. n. (ex Formicaleo).

The patterns of admixture, divergence, and ancestry of African cattle populations determined from genome-wide SNP data

BackgroundHumpless Bos taurus cattle are one of the earliest domestic cattle in Africa, followed by the arrival of humped Bos indicus cattle. The diverse indigenous cattle breeds of Africa are derived from these migrations, with most appearing to be hybrids between Bos taurus and Bos indicus. The present study examines the patterns of admixture, diversity, and relationships among African cattle breeds.MethodsData for ~ 40 k SNPs was obtained from previous projects for 4089 animals representing 35 African indigenous, 6 European Bos taurus, 4 Bos indicus, and 5 African crossbred cattle populations. Genetic diversity and population structure were assessed using principal component analyses (PCA), admixture analyses, and Wright’s F statistic. The linkage disequilibrium and effective population size (Ne) were estimated for the pure cattle populations.ResultsThe first two principal components differentiated Bos indicus from European Bos taurus, and African Bos taurus from other breeds. PCA and admixture analyses showed that, except for recently admixed cattle, all indigenous breeds are either pure African Bos taurus or admixtures of African Bos taurus and Bos indicus. The African zebu breeds had highest proportions of Bos indicus ancestry ranging from 70 to 90% or 60 to 75%, depending on the admixture model. Other indigenous breeds that were not 100% African Bos taurus, ranged from 42 to 70% or 23 to 61% Bos indicus ancestry. The African Bos taurus populations showed substantial genetic diversity, and other indigenous breeds show evidence of having more than one African taurine ancestor. Ne estimates based on r2 and r2adj showed a decline in Ne from a large population at 2000 generations ago, which is surprising for the indigenous breeds given the expected increase in cattle populations over that period and the lack of structured breeding programs.ConclusionAfrican indigenous cattle breeds have a large genetic diversity and are either pure African Bos taurus or admixtures of African Bos taurus and Bos indicus. This provides a rich resource of potentially valuable genetic variation, particularly for adaptation traits, and to support conservation programs. It also provides challenges for the development of genomic assays and tools for use in African populations.

Tracing the mutated HTT and haplotype of the African ancestor who spread Huntington disease into the Middle East

PurposeWe aimed to determine the origin and genetic characteristics of Huntington disease (HD) in the Middle East. MethodsWe performed genetic and genealogical analyses to establish the ancestral origin of the HTT pathgenic variant from a large kindred from Oman (hereafter called the OM-HD-01 pedigree) by single-nucleotide polymorphism and dense haplotype analysis genotyping. ResultsWe traced the oldest ancestry of the largest, eight-generation, OM-HD-01 pedigree (n=302 subjects, with 54 showing manifest HD) back to sub-Saharan Africa and identified a unique HD haplotype carried by all pedigree members, which consisted of portions of the C6 and C9 haplotypes and was carried by all affected members. Such a unique HD haplotype was of African origin and appeared to be associated with large CAG repeat expansions on average and high frequency of juvenile-onset HD. Three other families from the same area were also identified and found carrying a Caucasian HD haplotype A, also shared by most families of Arab ancestry. ConclusionMutated HTT spread into Middle East with a unique haplotype of African origin, appeared to be associated with juvenile-onset, a HD condition frequently occurring in Black Africans, and may have a significant impact on further development of novel targeted genetic therapies.

Ethnic and geographic diversity of chronic lymphocytic leukaemia.

East Asians, Asian Indians and Amerindians have a five to ten-fold lower age-adjusted incidence rate (AAIR) of chronic lymphocytic leukaemia (CLL) compared with persons of predominately European descent. The data we review suggest a genetic rather than environmental basis for this discordance. All these populations arose from a common African Black ancestor but different clades have different admixture with archaic hominins including Neanderthals, Denisovans and Homo erectus, which may explain different CLL incidences. There are also some differences in clinical laboratory and molecular co-variates of CLL between these populations. Because the true age-adjusted incidence rate in African Blacks is unknown it is not possible to determine whether modern Europeans acquired susceptibility to CLL or the other populations lost susceptibility and/or developed resistance to developing CLL. We also found other B-cell lymphomas and T- and NK-cell cancers had different incidences in the populations we studied. These data provide clues to determining the cause(s) of CLL.

(re)Producing mtEve

In their 1987 Nature publication, “Mitochondrial DNA and Human Evolution,” Rebecca Cann, Mark Stoneking, and Allan C. Wilson gave a new reconstruction of human evolution on the basis of differences in mitochondrial DNA among contemporary human populations. This phylogeny included an African common ancestor for all human mitochondrial DNA (mtDNA) lineages, and Cann et al.’s reconstruction became known as the “Out of Africa” hypothesis. Since mtDNA is inherited exclusively through the maternal line, the common ancestor who was first branded African Eve later became known as Mitochondrial Eve (mtEve, for short).In this paper, I show that mtEve was not a single, successful, or purely scientific discovery. Instead, she was produced many times and in many ways, each of which informed the next. Importantly, though Wilson and colleagues heralded mitochondrial DNA as a source of certainty, objectivity, and consensus for evolutionary inference, their productions of Mitochondrial Eve depended as much on popular assumptions about the certainty of maternal inheritance as they did on new molecular and computational tools. This recognition lets us reevaluate the complex consequences of these productions, which, like mtEve herself, could not be confined to a purely social, material, or scientific dimension.

Phylogenetic relationships in Bulbostylis (Abildgaardieae: Cyperaceae) inferred from nuclear and plastid DNA sequence data

Previous molecular phylogenetic analyses of the family Cyperaceae based on rbcL sequences showed Bulbostylis as paraphyletic, with B. atrosanguinea and B. hispidula forming a clade with Nemum spadiceum. On the contrary, phylogenetic analyses of the tribe Abildgaardieae based on nuclear (ITS ribosomal region) and plastid sequences (trnL-F region) showed Bulbostylis as monophyletic, although they only incorporated four species of Bulbostylis and none of Nemum. In this work, we presented a phylogenetic hypothesis of Bulbostylis based on a comprehensive sampling, including species from different continents for the first time. New sequences of Abildgaardia, Crosslandia, Fimbristylis, and Nemum were included to test the monophyly of Bulbostylis. In total, 84 sequences of both ITS and trnL regions were generated. Analyses were performed using Bayesian inference, maximum likelihood, and parsimony. Ancestral state reconstruction was performed using ML, MCMC, and parsimony methods. In all analyses, Bulbostylis resulted paraphyletic as Nemum atracuminatum is nested within it. Most American species of Bulbostylis grouped together, but relationships amongst them appeared poorly resolved. Ancestral state reconstructions of native distribution suggest an African ancestor of Bulbostylis, with at least three introduction independent events of the species in America. Morphological diagnostic characters such as the ‘style base permanence or detachment from the ripe achene’, and the ‘micromorphological patterns of the achene surface’ are homoplastic in this phylogenetic context, and therefore unsuitable to propose infrageneric groupings within the Bulbostylis.

Fossil hominin shoulders support an African ape-like last common ancestor of humans and chimpanzees

Reconstructing the behavioral shifts that drove hominin evolution requires knowledge of the timing, magnitude, and direction of anatomical changes over the past ∼6-7 million years. These reconstructions depend on assumptions regarding the morphotype of the Homo-Pan last common ancestor (LCA). However, there is little consensus for the LCA, with proposed models ranging from African ape to orangutan or generalized Miocene ape-like. The ancestral state of the shoulder is of particular interest because it is functionally associated with important behavioral shifts in hominins, such as reduced arboreality, high-speed throwing, and tool use. However, previous morphometric analyses of both living and fossil taxa have yielded contradictory results. Here, we generated a 3D morphospace of ape and human scapular shape to plot evolutionary trajectories, predict ancestral morphologies, and directly test alternative evolutionary hypotheses using the hominin fossil evidence. We show that the most parsimonious model for the evolution of hominin shoulder shape starts with an African ape-like ancestral state. We propose that the shoulder evolved gradually along a single morphocline, achieving modern human-like configuration and function within the genus Homo. These data are consistent with a slow, progressive loss of arboreality and increased tool use throughout human evolution.

First Asian record of a late Pleistocene reduncine (Artiodactyla, Bovidae, Reduncini), Sivacobus sankaliai, sp. nov., from Gopnath (Miliolite Formation) Gujarat, India, and a revision of the Asian genus Sivacobus Pilgrim, 1939

ABSTRACTThe new species, Sivacobus sankaliai, from an assemblage dated <200 ka near Gopnath, northwestern India, constitutes the only record of the bovid tribe Reduncini (waterbuck and allies) outside Africa within ≤500 ka. The previous Asian reduncine record was assigned to at least six genera, with the latest known record from the Siwalik Pinjor Formation (India and Pakistan, ca. 2.7–0.6 Ma) and probably ≥1.7 Ma. Finding this unexpectedly late Asian reduncine prompted tests of two hypotheses: (1) the Gopnath form derives directly from an African lineage following immigration since 500 ka. (2) It is the last known survivor of an Asian monophyletic group. The evidence supports the second hypothesis. We find that Asian Plio–Pleistocene reduncines belong to only one genus, Sivacobus, of ≥3 Ma duration, and to only two species up to Pinjor times, S. palaeindicus and S. patulicornis, with now a third and later Pleistocene species added. We give a revised diagnosis of Sivacobus. There is a close, and probable sister-group, relationship of Sivacobus with Adenota, the African crown kob clade. Sivacobus arose from the same African ancestor as the kobs, which emigrated from Africa ca. 3.5 Ma ago and endured in Asia for ≥3 Ma. The African sister group survived to the present, whereas the Asian one almost did. The S. sankaliai discovery has resulted not only in an increase in morphological, taxonomic, and geographic diversity of the Asian Reduncini, but also—and importantly—in a significant extension of their duration. http://zoobank.org/urn:lsid:zoobank.org:pub:F1406EE1-9F60-4A77-82E8-4B77C4571A80

When caterpillars attack: biogeography and life history evolution of the Miletinae (Lepidoptera: Lycaenidae).

Of the four most diverse insect orders, Lepidoptera contains remarkably few predatory and parasitic species. Although species with these habits have evolved multiple times in moths and butterflies, they have rarely been associated with diversification. The wholly aphytophagous subfamily Miletinae (Lycaenidae) is an exception, consisting of nearly 190 species distributed primarily throughout the Old World tropics and subtropics. Most miletines eat Hemiptera, although some consume ant brood or are fed by ant trophallaxis. A well-resolved phylogeny inferred using 4915 bp from seven markers sampled from representatives of all genera and nearly one-third the described species was used to examine the biogeography and evolution of biotic associations in this group. Biogeographic analyses indicate that Miletinae likely diverged from an African ancestor near the start of the Eocene, and four lineages dispersed between Africa and Asia. Phylogenetic constraint in prey selection is apparent at two levels: related miletine species are more likely to feed on related Hemiptera, and related miletines are more likely to associate with related ants, either directly by eating the ants, or indirectly by eating hemipteran prey that are attended by those ants. These results suggest that adaptations for host ant location by ovipositing female miletines may have been retained from phytophagous ancestors that associated with ants mutualistically.

African origin for New World monkeys

Paleontology![Figure][1] South American silvery marmosets ( Mico argentatus ) had an African ancestor. PHOTO: © THOMAS MARENT/VISUALS UNLIMITED/CORBIS New World monkeys—smallish, flat-nosed primates with prehensile tails such as silvery marmosets, golden lion tamarins, and squirrel monkeys—have inhabited South America for at least 26 million years, but it is unclear when they arrived and where they originated. Many paleontologists suspect an African origin, based on skeletal resemblances to ancient African monkeys. Now, Bond et al. describe three 36 million-year-old fossil teeth found in the Peruvian Amazon that support this idea: The shape of the teeth and phylogenetic analyses link the fossils to monkeys that inhabited Africa during the late Eocene, about 38 million years ago. The discovery also pushes back the monkeys' arrival date—perhaps by vegetation raft across the Atlantic Ocean—by 10 million years. Nature , 10.1038/nature14120 (2014). [1]: pending:yes

The evolution of Momordica cyclic peptides.

Cyclic proteins have evolved for millions of years across all kingdoms of life to confer structural stability over their acyclic counterparts while maintaining intrinsic functional properties. Here, we show that cyclic miniproteins (or peptides) from Momordica (Cucurbitaceae) seeds evolved in species that diverged from an African ancestor around 19 Ma. The ability to achieve head-to-tail cyclization of Momordica cyclic peptides appears to have been acquired through a series of mutations in their acyclic precursor coding sequences following recent and independent gene expansion event(s). Evolutionary analysis of Momordica cyclic peptides reveals sites that are under selection, highlighting residues that are presumably constrained for maintaining their function as potent trypsin inhibitors. Molecular dynamics of Momordica cyclic peptides in complex with trypsin reveals site-specific residues involved in target binding. In a broader context, this study provides a basis for selecting Momordica species to further investigate the biosynthesis of the cyclic peptides and for constructing libraries that may be screened against evolutionarily related serine proteases implicated in human diseases.

Consequences of the trans-Atlantic slave trade on medicinal plant selection: plant use for cultural bound syndromes affecting children in Suriname and Western Africa.

Folk perceptions of health and illness include cultural bound syndromes (CBS), ailments generally confined to certain cultural groups or geographic regions and often treated with medicinal plants. Our aim was to compare definitions and plant use for CBS regarding child health in the context of the largest migration in recent human history: the trans-Atlantic slave trade. We compared definitions of four CBS (walk early, evil eye, atita and fontanels) and associated plant use among three Afro-Surinamese populations and their African ancestor groups in Ghana, Bénin and Gabon. We expected plant use to be similar on species level, and assumed the majority to be weedy or domesticated species, as these occur on both continents and were probably recognized by enslaved Africans. Data were obtained by identifying plants mentioned during interviews with local women from the six different populations. To analyse differences and similarities in plant use we used Detrended Component Analysis (DCA) and a Wald Chi-square test. Definitions of the four cultural bound syndromes were roughly the same on both continents. In total, 324 plant species were used. There was little overlap between Suriname and Africa: 15 species were used on two continents, of which seven species were used for the same CBS. Correspondence on family level was much higher. Surinamese populations used significantly more weedy species than Africans, but equal percentages of domesticated plants. Our data indicate that Afro-Surinamers have searched for similar plants to treat their CBS as they remembered from Africa. In some cases, they have found the same species, but they had to reinvent the largest part of their herbal pharmacopeia to treat their CBS using known plant families or trying out new species. Ideas on health and illness appear to be more resilient than the use of plants to treat them.

The endemic Atlantochrysa atlantica (McLachlan) (Neuroptera: Chrysopidae) on Atlantic Islands: African or American origin?

Atlantochrysa atlantica (McLachlan) is restricted to Madeira and the Canary Islands. To determine its origin, molecular and morphological methods were used to identify its closest relatives among 40 species of Chrysopidae in 23 genera. Phylogenetic analysis of nuclear DNA from PepCK, wg, and ATPase show monotypic Atlantochrysa in a clade that includes American Meleoma and African Cunctochrysa; within the clade, Atlantochrysa is the sister taxon of those two genera together. Adult morphology and proximity to Africa suggest an origin in Africa from a Cunctochrysa-like ancestor, while larval morphology and habits support an origin in the Western Hemisphere from a Meleoma-like ancestor. A Bayesian phylogenetic analysis places the origin of this clade at around 20 mya. Atlantochrysa probably evolved in the early Miocene from an African relative of either Cunctochrysa or Meleoma, or from a shared African ancestor of both genera lacking the trash-carrying suite of specialisations.

Forest elephant mitochondrial genomes reveal that elephantid diversification in Africa tracked climate transitions

Among elephants, the phylogeographic patterns of mitochondrial (mt) and nuclear markers are often incongruent. One hypothesis attributes this to sex differences in dispersal and in the variance of reproductive success. We tested this hypothesis by examining the coalescent dates of genetic markers within elephantid lineages, predicting that lower dispersal and lower variance in reproductive success among females would have increased mtDNA relative to nuclear coalescent dates. We sequenced the mitochondrial genomes of two forest elephants, aligning them to mitogenomes of African savanna and Asian elephants, and of woolly mammoths, including the most divergent mitogenomes within each lineage. Using fossil calibrations, the divergence between African elephant F and S clade mitochondrial genomes (originating in forest and savanna elephant lineages, respectively) was estimated as 5.5 Ma. We estimated that the (African) ancestor of the mammoth and Asian elephant lineages diverged 6.0 Ma, indicating that four elephantid lineages had differentiated in Africa by the Miocene-Pliocene transition, concurrent with drier climates. The coalescent date for forest elephant mtDNAs was c. 2.4 Ma, suggesting that the decrease in tropical forest cover during the Pleistocene isolated distinct African forest elephant lineages. For all elephantid lineages, the ratio of mtDNA to nuclear coalescent dates was much greater than 0.25. This is consistent with the expectation that sex differences in dispersal and in variance of reproductive success would have increased the effective population size of mtDNA relative to nuclear markers in elephantids, contributing to the persistence of incongruent mtDNA phylogeographic patterns.

Sideroblastic anemia, iron overload, andALAS2R452S in African-American males: Phenotype and genotype features of five unrelated patients

Sideroblastic anemia, iron overload, and<i>ALAS2</i>R452S in African-American males: Phenotype and genotype features of five unrelated patients

THE COEVOLUTION OF HUMAN HANDS AND FEET

Human hands and feet have longer, more robust first digits, and shorter lateral digits compared to African apes. These similarities are often assumed to be independently evolved adaptations for manipulative activities and bipedalism, respectively. However, hands and feet are serially homologous structures that share virtually identical developmental blueprints, raising the possibility that digital proportions coevolved in human hands and feet because of underlying developmental linkages that increase phenotypic covariation between them. Here we show that phenotypic covariation between serially homologous fingers and toes in Homo and Pan is not only higher than expected, it also causes these digits to evolve along highly parallel trajectories under episodes of simulated directional selection, even when selection pressures push their means in divergent directions. Further, our estimates of the selection pressures required to produce human-like fingers and toes from an African ape-like ancestor indicate that selection on the toes was substantially stronger, and likely led to parallel phenotypic changes in the hands. Our data support the hypothesis that human hands and feet coevolved, and suggest that the evolution of long robust big toes and short lateral toes for bipedalism led to changes in hominin fingers that may have facilitated the emergence of stone tool technology.