Please help keeping these websites open for everybody as long as possible
- Eocene fossils of the Adapoidea. Most primitive of all known primates resembling modern lemurs: large body size, 2-1-4-3 DF, small and vertically implanted incisors, large and sexually dimorphic canines, grasp-climbing adaptations in limbs, post-orbital bars, inflated petrosal bulla with suspended tympanic ring, molars often with lots of shearing crests (folivory?), mostly diurnal, mostly quadrupedal, no evidence of dental comb.
- Also, phyletic change. The gradual evolution of species involving an entire population rather than a branching event, as in cladogenesis: when enough changes have occurred and become stable in a population so that it is significantly differentiated from an ancestral population, a new species name may be assigned and the entire ancestral population can be considered extinct. A long-standing debate in anthropology concerns origins of anatomically modern humans. The fossil record of the past 2 million years shows modern humans evolving from earlier humans, often refered as archaic humans. However, evolutionary relashionship of modern humans to the various archaic species, as well as to earlier ancestors is not very clear. Did modern humans evolve via anagenesis from a single archaic species across the Old World, or did they first arise in Africa? If the latter, did modern populations expanding out of Africa replace the archaic human populations, or did they interbreed with them?
- Climbing. The term "antipronograde" was coined to better describe the body posture used by great apes (especially the orangutan) while moving in trees. This type of locomotion involves grasping multiple supports including vertical by all four limbs and permits a relatively large body mass.
- Altricial neonate
- Altricial neonate is a newborn animal who is born naked, underdeveloped, with the eyes and ears sealed by membranes. Altricial infants are usually born in litters, are highly dependent on parental care (the word is derived from the Latin root alere meaning "to nurse, to rear, or to nourish"). Examples of altricial neonates in placental mammals: most carnivores and many rodents. Infants of Primates (including human) are precocial.
- Alu retrotransposons
Retrotransposons are genetic elements that can amplify themselves in a
genome and are ubiquitous components of the DNA of many eukaryotic organisms.
Primates are distinguished from all other mammals by presence of Alu
Alu elements have amplified in primate genomes through a RNA-dependent mechanism,
termed retroposition, and have reached a copy number in excess of 500,000 copies per human genome.
Bennett EA et al. Genome Res. 2008 Dec;18(12)
Living and fossil anthropoids can be distinguished from prosimians on the basis of a number of shared derived features of the
skull and dentition. While a list of anthropoid synapomorphies can be generated,
fossil speciments are often fragmentary, and so do not preserve multiple anatomical complexes.
The traditional approach is consider fossil skulls showing full postorbital closure
(a bony partition "walling off" the orbit posteriorly so that the orbit forms a cup-shaped structure) to be
Miller ER et al. Am J Phys Anthropol. 2005.
- Any member of the Hominoidea, superfamily of primates, that includes three genera: Pongo (orangutangs), Gorilla, and Pan (chimpanzee).
- A derived characteristic of a clade. Any feature novel to a species and its descendants. Related terms: autapomorphy, synapomorphy, plesiomorphy, homoplasy.
- Archaic humans
The descendants of H. ergaster/H. erectus who
bridge the gap between the early humans (H. ergaster/H. erectus) and modern
humans (H. sapiens). The archaic humans had, on average, a brain size approaching
that of modern humans but differently shaped skull and larger face.
A number of specimens attributed to archaic humans are classified as H. heidelbergensis
(a species that lived in
parts of Africa, Europe and possibly Asia from about 800,000–200,000 years ago) and as
H. neanderthalensis (a species that lived in Europe and the Middle East about 130,000–28,000 years ago).
had a number of unique craniofacial traits that distinguish them from both, H. heidelbergensis and H.
sapiens. Genetic studies suggest that lineages of modern humans and Neanderthals diverged
about 500,000-700,000 years ago.
Relethford JH. Heredity. 2008 Jun.
- A distinctive anatomical feature, known as a derived trait, that is unique to a given terminal group. Related terms: apomorphy, synapomorphy, plesiomorphy, homoplasy.
- Os penis, an isolated bone located above the distal end of the urethra in the penis of many mammals; it is present in most primates, carnivores, and rodents; humans differ from all Old World monkeys and apes in complete absense of the penile bone
- Arm-swinging is a type of arboreal locomotion that involves considerable for- and hindlimbs mobility and suspensory postures. It is used by lesser apes (gibbons and siamangs) to travel from tree to tree by using swinging forces.
- Cerebral cortex
- The outer layer of the mammalian cerebrum, which is involved in proceses such as sensation, perception, cognition and language (in human).
- A monophyletic group - that is, a single common ancestor and all its descendants. Hominins is a clade.
- Effective ancestral population size
- Approximate number of breeding individuals that produce offspring that live to
reproductive age. It affects the rate of loss of genetic variation,
the efficiency of natural selection and the accumulation of beneficial and deleterious mutations.
It is frequently much smaller than the number of individuals in a population.
Effective population size of human-chimpanzee last common ancestors is estimated
to be about 104-157 thousand, whereas effective population of modern humans from which all
today humans are originated was about 10 thousand.
Marques-Bonet T, Ryder OA, Eichler EE. Sequencing primate genomes: what have we learned? Annu Rev Genomics Hum Genet. 2009;10:355-86.
- Endotheliochorial placentation
- Moderately invasive type of placentation where the uterine epithelium is eroded such that the chorion (the outermost membrane of the fetus) comes into direct contact with maternal blood vessels. Most carnivores have this type of placentation.
- Epitheliochorial placentation
- Least invasive type of placentation where the uterine epithelium and he chorion (the outermost membrane of the fetus) are adjacent but the uterine epithelium remains intact unlike in endotheliochorial and hemochorial types of placentation. placentation.
- Grade is a category based on the outcome of the evolutionary history rather than on the process of the evolutionary history. Taxa in the same grade are adapted to eat same sort of foods, share the same posture and mode of locomotion. Categorization into grades is somewhat subjective and debatable especially when evidence is sparse. According to Wood B. and Lonergan in review "The hominin fossil record: taxa, grades and clades", J. Anat. (2008) extant hominids and hominins can be tentatively divided into the following grades: Possible and probable hominins, Archaic hominins, Megadont archaic hominins, Pre-modern Homo and Anatomically modern Homo. Please see more about this classification and species of our ancestors in section Ancestral species.
- Hemochorial placentation
- Most invasive type of placentation where the adjacent maternal blood vessels are broken and chorion (the outermost membrane of the fetus) is directly bathed in maternal blood. This type of placentation is characteristic to apes, tarsiers, New World monkeys (Haplorrhini). Hyenas, hedgehogs, most rodents, armadillos and anteaters also have this type of placentation.
- Members of the lineage that includes genus Homo (humans) and genus Pan (chimpanzees) but not other apes (Ref. Dawkins R. The ancenstor's tale: a pilgrimage to the dawn of evolution. Houghton Miffin Company: Boston, 2004, pp. 16, 101, 138, 225; Bracha HS. Progress in Neuro-Psychopharmacology & Biological Pscychiatry 30, 2006, pp. 827-853)
- Members of the lineage of humans ("human branch") following split (divergence) of genus Homo with genus Pan from their most recent common ancestor about 5 million years ago (Ref. Dawkins R. The ancenstor's tale: a pilgrimage to the dawn of evolution. Houghton Miffin Company: Boston, 2004, pp. 16, 101, 138, 225; Bracha HS. Progress in Neuro-Psychopharmacology & Biological Pscychiatry 30, 2006, pp. 827-853)
- Similarity due to the common origin.
- Similarity due to convergent evolution from adaptation to similar environments. Related terms: autapomorphy, apomorphy, synapomorphy, plesiomorphy.
- Arboreal bipedalism is the form of bipedal locomotion used on tree branches during foraging or travel. It is considered as a transition from which terrestrial bipedalism evolved. The hylobatian model is distinct in predicting a relatively small body mass and long hindlimbs.
- All the material of a species available to a taxonomist (http://zipcodezoo.com/Glossary/hypodigm.asp).
- The specialized upper portion of the respiratory tract that houses the vocal chords - folds of mucous membrane that provide the source for vocal sounds. The low position of the larynx in adult humans allows a rich phonetic repertoire, but its significance for language evolution remains a matter of debate.
- Last Common Ancestor (LCA)
- The most recent common ancestor of any two clades
(group of organisms, such as species)
that came to be separated by a species barrier. In human evolution, this is
some ancient species of extant ape that stood at the foundation of
two evolutionary branches - Pan (chimpanzee) and Homo.
The current fossil record indicates that Pan-Homo last
common ancestor existed at least 5 million years ago and most likely
between 6 and 7 million years ago (most conservative estimate allows
for a wide margin - between 4 and 8
million years ago).
The LCA is presumed to have locomotor system adapted to arboreality, probably some knuckle-walking while on the grounds and, possibly, some bursts of bipedalism. This would have been combined with projecting faces accomodating elongated jaws bearing relatively small chewing teeth and large canine teeth.
- The vocabulary and word forms of a language.
- Shedding of blood and debris from the uterine at the end of ovarian cycle. Because of its approximate monthly occurence, this is commonly known as menstruation. Simian (Haplorrhini) typically exhibit some form of menstruation with considerable variation in degree of bleeding (from microscopic evidence to heavy blood loss in humans). Apart from simian primates, menstruation also exists in bats. The evolutionary role of menstruation is still uncertain, at least there is no consensus among researchers.
- One mating systems of the living primates, where female and male form a pair, i.e. an individual has one mate in a relationship (some New and Old World monkeys, gibbon)
- Naked ape
- Great book by Desmond Morris "The Naked Ape: A Zoologist's Study of the Human Animal" (1967) where the author looks at humans as an ordinary albeit very successfull animal species and compares them to other animals.
- Eocene fossils of the Omomyoidea. Generally tarsier-like in many respects: large, procumbent lower incisor, small canines, unfused mandibular symphysis, large eyes reflect nocturnality with tapetum lucidum, inflated petrosal auditory bulla with attached tympanic ring that forms a bony tube, moderately elongated calcaneus in some, and partially fused tibia and fibula in some, small to tiny body size in most (some late forms are large). Nocturnal, leaping, insectivorous and frugivorous.
- A membranous vascular organ that develops in female mammals during pregnancy, lining the uterine wall and partially enveloping the fetus, to which it is attached by the umbilical cord. Following birth, the placenta is expelled. (Answers.com)
- Type and structure of plscenta. The basic classification of placenta types originally proposed by Grosser (Vergleichende Anatomie und Entwicklungsgeschichte der Eihäute und der Placenta. 1909). This classification is based on the degree to which the placenta invades the internal lining of the uterus. Three types of placentation:
- A character state that is present in both outgroups and in the ancestors. Features shared more widely than in a group of interest (for example, all primates are mammals). Related terms: autapomorphy, synapomorphy, apomorphy, homoplasy.
- Very rare mating systems of the living primates, a form of polygamy, where one female has multiple sexual male partners (some New World monkeys)
- Also promiscuity, one mating systems of the living primates, a form of polygamy, where females and males are mating freely (chimpanzee, some New World monkeys)
- One of mating systems of the living primates, a form of polygamy, where one male has multiple sexual female partners (lemurs, some New and Old World monkeys, gorilla)
- Positive selection
- When a novel allele that increases the fitness of an organism becomes more prevalent in the population.
- Quadrupedality. Walking with the long axis of the body parallel to the ground, which is characteristic for digitigrade, palmigrade, fist- and knuckle-walking quadrupeds.
- Purifying selection
- Selection against alleles that have harmful phenoty[ic effects, which leads to their loss from the population.
- Precocial neonate
Precocial (unlike altricial) neonates are born well developed, hairy, with
the eyes and ears open, very often they are mobile and to some degree independent.
Precocial neonates are found in herbivores, some rodents, and primates.
In precocial mammals, the eyes and ears become sealed with membranes, at a stage of development
that would correspond to birth of an altricial mammal, and then reopen
again around the time of birth.
Human neonates are undoubtedly precocial because humans, like other primates, typically produce single well-developed neonate with eyes and ears open at birth following a relatively lengthy gestation period. However, human neonates are commonly labeled as "altricial" because of their helplessness and lack of body hairs (late in intrauterine development, the human fetus does have a covering of fine, soft body hair, which is usually shed during the 7th or 8th month of pregnancy). The helplessness of newborn humans is attributable to the fact that their brain development at birth is far less advanced in comparison with other primates.
- A member of the biological order Primates that includes non-hominid primates (monkeys), and hominid primates (apes), and genus Homo.
- A process by which indefinitely more complex structures are generated through the repeated recombination of simpler structures and elements. Debates continues about whether recursion represents the only component that is genuinely new in communicaions (i.e. language) of the human species. [citation]
- Segmental duplications (SDs)
- Also known as Low Copy Repeates (LCRs). Segments of DNA greater than 1kbp in length with high sequence identity (>90%) that typically map to two or more locations in the genome. SDs are considered one of the two main features (the other being retrotransposons) that is responsible for the abundance of large-scale structural variation observed in primate genomes.
- Sagittal crest
- A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are exceptionally strong jaw muscles. The sagittal crest serves primarily for attachment of the stemporalis muscle, which is one of the main chewing muscles. Sagittal crests are found in robust great apes, and some early hominins (Paranthropus). Prominent sagittal crests are found among male gorillas and orangutans. The largest sagittal crest ever discovered in the human lineage belongs to the "Black Skull", Paranthropus aethiopicus field number KNM WT 17000, the earliest known robust hominid ancestor and the oldest robust australopithecine discovered to date. The prominence of the crest appears to have been an adaptation for the aethiopicus's heavy chewing. (Wikipedia: sagittal crest)
- a trait that is found in some or all terminal groups of a clade, and inherited from a common ancestor, for which it was an autapomorphy (i.e., not present in its immediate ancestor). Related terms: apomorphy, autapomorphy, plesiomorphy, homoplasy.
- Fossils from one layer can represent artificial mixture that might have originated thousands of years apart. Remains of animals living in different habitats can be mixed by water and other natural processes. Further bias can be introduced by unsystematic recovery if, for example, only the more complete, identifiable, or rare specimens are collected. Taphonomy is the practice of deducing physical and biological conditions under which the fossils accumulated and the degree to which all envisioned biases operated under time of deposition.
- The reproductive gland in a male vertebrate that produces spermatozoa and hormones necessary in reproduction; humans have arguably smaller testicles relative to the body size than other primates; the reduction in testicle size might indicate an adaptation of early hominins to monogamous mating system (monogamy) where sperm competition is decreased (Ref. Martin RD, The evolution of Human Reproduction: A Primotological Perspective, Yearbook of physical anthropology 50:59-84, 2007)
- Vasovagal syncope (VVS)
- The most common type of syncope (fainting) that arguably is unique in humans. It is triggered by several stimuli, specifically, by severe stress and fear, sudden scare, hopelessness in a face of perceived imminent death or grave wounding, sight of blood, etc. It is characterized by loss of consciousness caused by "profound bradycardia" (slowed heart beat) accompanied not surprisingly by "diminished cerebral perfusion" (lack of blood in the brain).