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PubMed1993

Hominoid heterochromatin: terminal C-bands as a complex genetic trait linking chimpanzee and gorilla.

The genetic relations of the apes have been the source of contention throughout the last decade. A potentially useful suite of phylogenetic characters is the distribution of darkly staining material (heterochromatin) in the chromosomes of the apes. While the precise etiology of this character suite remains unclear, it appears to be fairly easily reconciled to hominoid phylogeny in general. The distribution of heterochromatin at the tips of the chromosomes of gorillas and chimpanzees suggests a phylogenetic association between those two taxa exclusive of humans.

Animals↗
PubMed1993

Torso morphology and locomotion in Proconsul nyanzae.

A new partial skeleton of Proconsul nyanzae from Mfangano Island, Kenya (KNM-MW 13142) includes five lumbar vertebrae, a partial sacrum, and nearly complete hipbone. Until recently, little was known of the axial and pelvic skeletons of Proconsul, or any early Miocene hominoid. Because torso morphology directly reflects locomotor behavior, these elements provide important new information about posture and locomotion of P. nyanzae. Two basic patterns of locomotor behavior and corresponding torso morphology exist among extant anthropoids. Monkeys have long, flexible spines with powerful epaxial muscles and mediolaterally narrow thoraces. This morphology represents a response to the mechanical requirements of habitual pronograde quadrupedalism. In contrast, hominoids, particularly great apes, have shorter, stiffer spines and broader torsos than do monkeys. The hominoid pattern reflects an emphasis on forelimb abduction-adduction, and on stability and control of the lower back during forelimb-dominated arboreal locomotion. KNM-MW 13142 had craniocaudally elongate vertebral bodies, and probably six lumbar vertebrae, reflecting a long, flexible vertebral column. The narrow, laterally facing iliac blades of KNM-MW 13142 imply the presence of a mediolaterally narrow, dorsoventrally deep thorax. Its wide iliac tuberosities, ventrally located lumbar transverse processes, and distinct accessory processes suggest that Proconsul nyanzae also had strap-like epaxial muscles similar to those characterizing most monkeys. Axial and pelvic morphology of KNM-MW 13142 indicate that P. nyanzae had not undergone an ape-like rearrangement of its torso to adapt to forelimb-dominated arboreality. Instead, P. nyanzae probably retained a more primitive pattern of pronograde quadrupedalism. This morphology indicates that the extant hominoid pattern of torso anatomy arose subsequent to the establishment of the hominid clade.

Animals↗
PubMed1994

Molecular evidence on primate phylogeny from DNA sequences.

Evidence from DNA sequences on the phylogenetic systematics of primates is congruent with the evidence from morphology in grouping Cercopithecoidea (Old World monkeys) and Hominoidea (apes and humans) into Catarrhini, Catarrhini and Platyrrhini (ceboids or New World monkeys) into Anthropoidea, Lemuriformes and Lorisiformes into Strepsirhini, and Anthropoidea, Tarsioidea, and Strepsirhini into Primates. With regard to the problematic relationships of Tarsioidea, DNA sequences group it with Anthropoidea into Haplorhini. In addition, the DNA evidence favors retaining Cheirogaleidae within Lemuriformes in contrast to some morphological studies that favor placing Cheirogaleids in Lorisiformes. While parsimony analysis of the present DNA sequence data provides only modest support for Haplorhini as a monophyletic taxon, it provides very strong support for Hominoidea, Catarrhini, Anthropoidea, and Strepsirhini as monophyletic taxa. The parsimony DNA evidence also rejects the hypothesis that megabats are the sister group of either Primates or Dermoptera (flying lemur) or a Primate-Dermoptera clade and instead strongly supports the monophyly of Chiroptera, with megabats grouping with microbats at considerable distance from Primates. In contrast to the confused morphological picture of sister group relationships within Hominoidea, orthologous noncoding DNA sequences (spanning alignments involving as many as 20,000 base positions) now provide by the parsimony criterion highly significant evidence for the sister group relationships defined by a cladistic classification that groups the lineages to all extant hominoids into family Hominidae, divides this ape family into subfamilies Hylobatinae (gibbons) and Homininae, divides Homininae into tribes Pongini (orangutans) and Hominini, and divides Hominini into subtribes Gorillina (gorillas) and Hominina (humans and chimpanzees). A likelihood analysis of the largest body of these noncoding orthologues and counts of putative synapomorphies using the full range of sequence data from mitochondrial and nuclear genomes also find that humans and chimpanzees share the longest common ancestry.

Animals↗
PubMed2005

Foramen magnum position variation in Pan troglodytes, Plio-Pleistocene hominids, and recent Homo sapiens: implications for recognizing the earliest hominids.

The anteroposterior position of the foramen magnum distinguishes living Homo sapiens from apes, and has been used as evidence for the hominid status of numerable fossils in the history of human paleontology. During the past decade, foramen magnum position has been cited as evidence of the hominid status of Ardipithecus and Sahelanthropus. Specifically, the basion of Ardpithecus is reported to be inline with the bicarotid chord, while the basion of Sahelanthropus is reported to both touch the biporion chord and intersect the bicarotid chord. In order to assess the effectiveness of anteroposterior foramen magnum position in distinguishing hominids from nonhominid apes, this study examined whether or not the positions of biporion and bicarotid relative to basion sufficiently distinguished Pan troglodytes from recent Homo sapiens and Plio-Pleistocene hominids. The distances from basion to the biporion chord (BSBIP) and from basion to the bicarotid chord (BSBIC) were measured on samples of chimpanzee (n = 69) and recent human (n = 42) crania and a sample of Plio-Pleistocene hominid fossils (n = 8). The data were used to test the hypothesis that BSBIP and BSBIC measurements do not sufficiently distinguish P. troglodytes from hominids. While basion to biporion (BSBIP) does not effectively distinguish P. troglodytes from Plio-Pleistocene hominids and humans when used univariately, basion to bicarotid (BSBIC), when used univariately or bivariately with BSBIP, can be used to test whether or not an unknown specimen is a hominid. These results are used to evaluate the hominid status of Ardipithecus and Sahelanthropus.

Animals↗
PubMed2005

Bilateral asymmetry in the limb bones of the chimpanzee (Pan troglodytes).

There is much debate in behavioral primatology on the existence of population-level handedness in chimpanzees. The presence or absence of functional laterality in great apes may shed light on the origins of human handedness and on the evolution of cerebral asymmetry. The plasticity of long bone diaphyses in response to mechanical loading allows the functional interpretation of differences in cross-sectional geometric. While left-right asymmetry in upper limb diaphyseal morphology is a known property in human populations, it remains relatively unexplored in apes. We studied bilateral asymmetry in 64 skeletons of wild-caught chimpanzee using the humerus, second metacarpal, and femur. The total subperiosteal area (TA) of the diaphyses was measured at 40% of maximum humeral length and at the midshaft of the metacarpals and femora using external silicone molds. Overall, the TA values of the left humeri were significantly greater than the right, indicating directional asymmetry. This effect was even greater when the magnitude of difference in TA between each pair of humeri was compared. The right second metacarpals showed a tendency toward greater area than did the left, but this did not reach statistical significance. The lack of asymmetry in the femur serves as a lower limb control, and suggests that the upper limb results are not a product of fluctuating asymmetry. These findings imply behavioral laterality in upper limb function in chimpanzees, and suggest a complementary relationship between precision and power.

Anatomy, Cross-Sectional↗
PubMed2006

Relationship between formation of the femoral bicondylar angle and trochlear shape: independence of diaphyseal and epiphyseal growth.

During hominin evolution, an increase in the femoral bicondylar angle was the initial change that led to selection for protuberance of the lateral trochlear lip and the elliptical profile of the lateral condyle. No correlation is found during ontogeny between the degree of femoral obliquity and of the prominence of the lateral trochlear lip. Might there be a relationship with the elliptical profile of the lateral condyle? On intact femoral diaphyses of juvenile humans and great apes, we compared the anteroposterior length of the lateral and medial sides of the distal metaphysis. The two diaphyseal pillars remain equal during postnatal growth in great apes, while the growth of the lateral pillar far exceeds that of the medial pillar in humans. Increase in bicondylar angle is correlated with disproportionate anteroposterior lengthening of the lateral pillar. The increased anteroposterior length of the lateral side of the metaphysis would contribute to increasing the radius of the curvature of the lateral condyle, but not to the projection of the lateral trochlear lip. The similar neonatal and adult femoro-patellar joint shape in humans prompted an assessment of the similarity during growth of the entire neonatal and adult epiphyses. We showed that the entire epiphysis undergoes drastic changes in proportions during postnatal growth. Finally, we emphasize the need to distinguish the cartilaginous phenotype and the ossified phenotype of the distal femoral epiphysis (and of any epiphysis) during postnatal growth. This crucial distinction applies to most postcranial bones, for they almost all develop following the process of endochondral ossification.

Adaptation, Physiological↗
PubMed2006

Life history, enamel formation, and linear enamel hypoplasia in the Ceboidea.

Linear enamel hypoplasia (LEH), a developmental defect of enamel, increases in frequency from prosimian to monkey to lesser ape to great ape grades (Guatelli-Steinberg 2000 Am. J. Phys. Anthropol. 112:395-410, [2001] Evol. Anthropol. 10:138-151; Newell 1998 Ph.D. dissertation, Temple University). This taxonomic pattern in the distribution of LEH is closely related to maturation length across the primate order (Newell 1998 Ph.D. dissertation, Temple University, 2000 Am. J. Phys. Anthropol. [Suppl.] 30:236). Longer maturation periods are associated with higher LEH frequencies; they appear to provide greater opportunity for defects to form. The present study explores the relationship between maturation length and LEH frequency within the Ceboidea. Because of its prolonged period of growth, Cebus is predicted to manifest LEH at a higher frequency than the more rapidly maturing ceboid genera. To test this hypothesis, two separate researchers (E.A.N. and D.G.-S.) examined LEH in nonoverlapping museum series of ceboids. The results support the hypothesis: in 13 genera (n = 1,276), E.A.N. found that LEH frequencies ranged from 0% in Callicebus, Cebuella, and Saimiri to 20% in Cebus. D.G.-S. found similar frequencies among five genera (n = 107), from 0% in Saimiri to 32% in Cebus. Thus, the broad pattern of LEH distribution evident across major taxonomic groups of primates is repeated within the Ceboidea. We also examined a related hypothesis linking the spacing of perikymata, which is influenced by enamel extension rates (Shellis 1998 J. Hum. Evol. 35:387-400), to LEH. The most likely areas of tooth crowns to exhibit LEH in human teeth are those in which perikymata are most closely spaced (Hillson and Bond 1997 Am. J. Phys. Anthropol. 104:89-103). We hypothesized that the longer-maturing Cebus, with its elevated LEH frequency, will also exhibit more closely spaced perikymata than other ceboids. Analysis of a small microscopic subsample (n = 8) lends limited support to this second hypothesis.

Animals↗
PubMed2006

Khoratpithecus piriyai, a Late Miocene hominoid of Thailand.

A Khoratpithecus piriyai lower jaw corresponds to a well-preserved Late Miocene hominoid fossil from northeastern Thailand. Its morphology and internal structure, using a microcomputed tomography scan, are described and compared to those of other known Miocene hominoids. It originated from fluviatile sand and gravel deposits of a large river, and was associated with many fossil tree trunks, wood fragments, and large vertebrate remains. A biochronological analysis by using associated mammal fauna gives an estimated geological age between 9-6 Ma. The flora indicates the occurrence of a riverine tropical forest and wide areas of grassland. K. piriyai displays many original characters, such as the great breadth of its anterior dentition, suggesting large incisors, large lower M3, a canine with a flat lingual wall, and symphysis structure. Several of its morphological derived characters are shared with the orangutan, indicating sister-group relationship with that extant ape. This relationship is additionally strongly supported by the absence of anterior digastric muscle scars. These shared derived characters are not present in Sivapithecus, Ankarapithecus, and Lufengpithecus, which are therefore considered more distant relatives to the orangutan than Khoratpithecus. The Middle Miocene K. chiangmuanensis is older, displays more primitive dental characters, and shares several dental characters with the Late Miocene form. It is therefore interpreted as its probable ancestor. But its less enlarged M3 and more wrinkled enamel may suggest an even closer phylogenetic position to orangutan ancestors, which cannot yet be supported because of the incomplete fossil record. Thus Khoratpithecus represents a new lineage of Southeast Asian hominoids, closely related to extant great ape ancestors.

Animals↗
PubMed1976

Logarithmic growth of the hominoid mandible.

The growth of the basal unit of the mandible was studied by plotting the position, relative to the median plane, of the oval, mandibular and mental foramina in immature and adult skulls of Man, chimpanzee and gorilla. In Man, the basal unit was found to grow out along a constant logarithmic spiral. In the apes, the basal unit grew along a constant logarithmic spiral, the amount of unfolding being greater in the gorilla than in the chimpanzee. It is argued that the mode of growth seen in the apes evolved, as these forms became more prognathous, because it requires less compensatory rotation of the mandible, while the mode seen in Man is probably closer to that which occurred in common ancestral form.

Adult↗
PubMed1977

Sperm/egg interaction: the specificity of human spermatozoa.

Human spermatozoa display unusually limited affinities in their interaction with oocytes of other species. They adhered to and, when capacitated, penetrated the vestments of the oocyte of an ape--the gibbon, Hylobates lar--both in vivo and in vitro. On the other hand, human spermatozoa would not even attach to the zona surface of sub-hominoid primate (baboon, rhesus monkey, squirrel monkey), nor to the non-primate eutherian oocytes tested. Among the apes the gibbon stands furthest from man. Thus, although the specificity of human spermatozoa is not confined to man alone, it probably is restricted to the Hominoidea. This study also suggests that the evolution of man and perhaps the other hominids has been accompanied by a restrictive change in the nature of the sperm surface which has limited and made more specific the complementary surface to which their spermatozoa may adhere. For the failure of human spermatozoa to attach to the zona surface of all non-hominoid oocytes stands in contrast to the behaviour of spermatozoa of the several other mammals studied which, in most combinations, adhered readily to foreign oocytes, including those of man. Taxonomically, the demonstration of a compatibility between the gametes of man and gibbon, not shared with cercopithecids, constitutes further evidence for inclusion of the Hylobatidae within the Hominoidea.

Animals↗
PubMed1996

Two mathematically defined expressive language structures in humans and chimpanzees.

Two expressive language structures have been identified mathematically in humans and chimpanzees. The first was found by measuring the waiting times between the invocation of new words or symbols, which consistently yielded individually characteristic rate constants and descending exponential curves that reflect a stochastically lawful Poisson process. The second was discovered by calculating the cumulative informational complexity (entropy) of word usage, which in all cases was a deterministically lawful logarithmic function of the number of words used to a given point in a communicative sequence. Individual and species differences in how this law is obeyed also characterized the sample. The results from the apes resembled those from the works of human poets like Shakespeare. The findings speak for deep, natural, unlearned expressive language structures in apes that are comparable to those seen in humans.

Animals↗
PubMed1990

Language acquisition in a nonhuman species: implications for the innateness debate.

This article approaches the linguistic innateness issue from the perspective of a nonhuman species, the bonobo, an ape which is generally taken to be the best living model for early hominids. Recent studies indicate that a bonobo reared with humans comes spontaneously to comprehend spoken words, to produce novel two word combinations, and to respond appropriately to syntactically ordered sentences. The difference between the use of word combinations to say what one word can accomplish and combinations that convey a novel idea not transmittable by a single word is emphasized. It is argued that the use of such novel combinations must have preceded the appearance of syntax in the evolution of language. The use of multiword novel combinations has not received sufficient attention in the literature because of the erroneous assumption that novel meanings could only be achieved through syntactical structure. Consequently the significance of the ape's linguistic competence has been severely undervalued.

Animal Communication↗
PubMed1993

Binding of amino acid side chains to preformed cavities: interaction of serine proteinases with turkey ovomucoid third domains with coded and noncoded P1 residues.

In the association of serine proteinases with their cognate substrates and inhibitors an important interaction is the fitting of the P1 side chain of the substrate or inhibitor into a preformed cavity of the enzyme called the S1 pocket. In turkey ovomucoid third domain, which is a canonical protein proteinase inhibitor, the P1 residue is Leu18. Here we report the values of equilibrium constants, Ka, for turkey ovomucoid third domain and 13 additional Leu18X variants with six serine proteinases: bovine alpha chymotrypsin A, porcine pancreatic elastase, subtilisin Carlsberg, Streptomyces griseus proteinases A and B, and human leukocyte elastase. Eight of the Xs are coded amino acids: Ala, Ser, Val, Met, Gln, Glu, Lys, and Phe, and five are noncoded: Abu, Ape, Ahx, Ahp, and Hse. They were chosen to simplify the interamino acid comparisons. In the homologous series of straight-chain side chains Ala, Abu, Ape, Ahx, Ahp, free energy of binding decreases monotonically with the side-chain length for chymotrypsin with large binding pocket, but even for this enzyme shows curvature. For the two S. griseus enzymes a minimum appears to be reached at Ahp. A minimum is clearly evident for the two elastases, where increasing the side-chain length from Ahx to Ahp greatly weakens binding, but much more so for the apparently more rigid pancreatic enzyme than for the more flexible leukocyte enzyme. beta-Branching (Ape/Val) is very deleterious for five of the six enzymes; it is only slightly deleterious for the more flexible human leukocyte elastase. The effect of gamma-branching (Ahx/Leu), of introduction of heteroatoms (Abu/Ser), (Ape/Hse), and (Ahx/Met), and of introduction of charge (Gln/Glu) and (Ahp/Lys) are tabulated and discussed. An important component of the free energy of interaction is the distortion of the binding pocket by bulky or branched side chains. Most of the variants studied were obtained by enzymatic semisynthesis. X18 variants of the 6-18 peptide GlyNH2 were synthesized and combined with natural reduced peptide 19-56. Disulfide bridges were formed. The GlyNH2 was removed and the reactive-site peptide bond X18-Glu19 was synthesized by complex formation with proteinase K. The resultant complexes were dissociated by sudden pH drop. This kinetically controlled dissociation afforded virgin, reactive-site-intact inhibitor variants.

Amino Acid Sequence↗
PubMed2004

High-throughput simultaneous determination of plasma water deuterium and 18-oxygen enrichment using a high-temperature conversion elemental analyzer with isotope ratio mass spectrometry.

This paper presents a high-throughput method for the simultaneous determination of deuterium and oxygen-18 (18O) enrichment of water samples isolated from blood. This analytical method enables rapid and simple determination of these enrichments of microgram quantities of water. Water is converted into hydrogen and carbon monoxide gases by the use of a high-temperature conversion elemental analyzer (TC-EA), that are then transferred on-line into the isotope ratio mass spectrometer. Accuracy determined with the standard light Antartic precipitation (SLAP) and Greenland ice sheet precipitation (GISP) is reliable for deuterium and 18O enrichments. The range of linearity is from 0 up to 0.09 atom percent excess (APE, i.e. -78 up to 5725 delta per mil (dpm)) for deuterium enrichment and from 0 up to 0.17 APE (-11 up to 890 dpm) for 18O enrichment. Memory effects do exist but can be avoided by analyzing the biological samples in quintuplet. This method allows the determination of 1440 samples per week, i.e. 288 biological samples per week.

Administration, Oral↗
PubMed2005

Isotope ratio monitoring of small molecules and macromolecules by liquid chromatography coupled to isotope ratio mass spectrometry.

In the field of isotope ratio mass spectrometry, the introduction of an interface allowing the connection of liquid chromatography (LC) and isotope ratio mass spectrometry (IRMS) has opened a range of new perspectives. The LC interface is based on a chemical oxidation, producing CO2 from organic molecules. While first results were obtained from the analysis of low molecular weight compounds, the application of compound-specific isotope analysis by irm-LC/MS to other molecules, in particular biomolecules, is presented here. The influence of the LC flow rate on the CO2 signal and on the observed delta13C values is demonstrated. The limits of quantification for angiotensin III and for leucine were 100 and 38 pmol, respectively, with a standard deviation of the delta13C values better than 0.4 per thousand. Also, accuracy and precision of delta13C values for elemental analyser-IRMS and flow injection analysis-IRMS (FIA-LC/MS) were compared. For compounds with molecular weights ranging from 131 to 66,390 Da, precision was better than 0.3 per thousand, and accuracy varied from 0.1 to 0.7 per thousand. In a second part of the work, a two-dimensional (2D)-LC method for the separation of 15 underivatised amino acids is demonstrated; the precision of delta13C values for several amino acids by irm-LC/MS was better than 0.3 per thousand at natural abundance. For labelled mixtures, the coefficient of variation was between 1% at 0.07 atom % excess (APE) for threonine and alanine, and around 10% at 0.03 APE for valine and phenylalanine. The application of irm-LC/MS to the determination of the isotopic enrichment of 13C-threonine in an extract of rat colon mucosa demonstrated a precision of 0.5 per thousand, or 0.001 atom %.

Amino Acids↗
PubMed2006

Toxicity of nonylphenol on the cnidarian Hydra attenuata and environmental risk assessment.

Alkylphenols and their derivatives, alkylphenol polyethoxylates (APEs), are synthetic chemicals of concern owing to their endocrine properties. Nonylphenol (NP) is a critical APE metabolite because of its recalcitrance to biodegradation, toxicity, and ability to bio-accumulate in aquatic organisms. Studies of NP effects in vertebrates demonstrated estrogenic disrupting properties in fish, birds, reptiles, and mammal cells in which NP displaces the natural estrogen from its receptor. Less is known on its toxicity toward invertebrates. Effects on reproduction have been reported, but toxicity on development has been poorly documented thus far. We investigated NP toxicity on survival and regeneration of the freshwater coelenterate Hydra attenuata. Hydra is known for its regenerative capacity and its sensitivity to chemical pollution. It has been used for over 20 years to screen for teratogenicity of chemicals (Johnson et al. (1982) Teratog Carcinog Mutagen 2:263-276). Our results showed that hydra appeared as one of the most sensitive species to acute and chronic toxicity of NP compared to several freshwater invertebrates. Regeneration was disrupted at NP concentrations lower than those affecting survival. Toxicity thresholds of NP for aquatic vertebrates and invertebrates are also reported and discussed in the context of environmental risk assessment and of water quality objectives recommended for surface waters in industrialized countries. NP levels have decreased during the last decade because of a voluntary agreement of surfactant producers and users. At present, concentrations of NP found in surface waters are far below 1 microg/L in Europe, but can reach several microg/L when wastewater treatment plant inefficiency occurs.

Animals↗
PubMed2002

The nucleotide sequences of the parathyroid gene in primates (suborder Anthropoidea).

Nucleotide sequences of the parathyroid (PTH) gene of 12 species of primates belonging to suborder Anthropoidea were examined. The PTH gene contains one intron that separates two exons that code the sequence of prepro and PTH, respectively. The intron of the PTH gene in Cebus apella, Callithrix jacchus, and Saguinus oedipus was 102 bp long, whereas a 103-bp intron was observed in the remaining species. Phylogenetic analysis using the nucleotide sequences of PTH revealed that these 12 species of primates of suborder Anthropoidea could be divided into two groups of the infraorder Platyrrhini (C. apella, C. jacchus, and S. oedipus) and the infraorder Catarrhini (Macaca fascicularis, Macaca fuscata, Cercopithecus aethiops, Papio hamadryas, Presbytes obscura, Hylobates lar, Pongo pygmaeus, Pan troglodytes, and Pan paniscus). The latter infraorder could be further subdivided into two subgroups belonging to the superfamily Cercopithecoidea (M. fascicularis, M. fuscata, C. aethiops, P. hamadryas, and P. obscura) and the superfamily Hominoidea (H. lar, P. pygmaeus, P. troglodytes, and P. paniscus). The deduced amino acid sequences of PTH gene between 12 species of nonhuman primates and human revealed no amino acid substitution in mature PTH among orangutans, chimpanzees, and humans. The results indicated that the PTH gene is very conserved among primates, especially between great apes and humans. The apes are the most suitable animals to be used for studying the bone metabolism and applying the knowledge to clinical use in humans.

Amino Acid Sequence↗
PubMed1999

Primate evolution of an olfactory receptor cluster: diversification by gene conversion and recent emergence of pseudogenes.

The olfactory receptor (OR) subgenome harbors the largest known gene family in mammals, disposed in clusters on numerous chromosomes. We have carried out a comparative evolutionary analysis of the best characterized genomic OR gene cluster, on human chromosome 17p13. Fifteen orthologs from chimpanzee (localized to chromosome 19p15), as well as key OR counterparts from other primates, have been identified and sequenced. Comparison among orthologs and paralogs revealed a multiplicity of gene conversion events, which occurred exclusively within OR subfamilies. These appear to lead to segment shuffling in the odorant binding site, an evolutionary process reminiscent of somatic combinatorial diversification in the immune system. We also demonstrate that the functional mammalian OR repertoire has undergone a rapid decline in the past 10 million years: while for the common ancestor of all great apes an intact OR cluster is inferred, in present-day humans and great apes the cluster includes nearly 40% pseudogenes.

Animals↗