Biological Anthropology • Biological evolution is the background for culture as a method of adaptation to physical environmental conditions. • Human evolution is a story of co-evolution: cultural and biological change reinforcing one another.
Basic Hominid Adaptations • Bipedalism • Orthograde posture • Rotation and narrowing of the pelvis • All were biological adaptations that provided some of our ancestors with unique reproductive advantages.
Orthograde apes • Those advantages came before the increase in brain size that we associate with the development of humans. The earliest human ancestors, then, were orthograde apes.
Increase in Brain Size • Development of the brain case in Australopithecus produced other advantages – an increase in the capacity for tool making, implying better communication skills. Note the italics. • With Homo erectus, there is further expansion of the brain and greater control of lithic resources.
By the Middle Paleolithic, the Levallois method had transformed tool making into manufacturing. • With the development of H. sapiens sapiens, 40 kya, the point of “cultural take-off” was reached (Harris 1999).
Cultural Take-Off • Major cultural changes prior to the take-off point were tied to changes in the skeleton. • Since the Upper Paleolithic, cultural change has been independent of biological change – though biological adaptations continue.
The Idea of Evolution • Carolus Linnaeus (1707-1778) publishes the first edition of Systema Naturae (1735). • Eleven pages. The 13th edition was published in 1770, with 3000 pages. • Whales with mammals, and monkeys with humans • No evolutionary scheme.
Georges-Louis Leclerc • Georges-Louis Leclerc, Comte de Buffon (1707-1788). • Discussed the similarities between humans and apes in his Historie Naturelle – 44 volumes (1749 – 1804). • Anticipated Charles Lyell’s work by challenging the accepted age of the Earth.
George Cuvier (1769-1832) • Established the field of vertebrate paleontology. • Established the fact of extinction. • In Discours sur les revolutions de la surface du globe, et sur les changemens qu'elles ont produits dans le regne animal (1825), Cuvier argued for catastrophism. • A variety of catastrophism is the modern explanation for the Cretaceous-Tertiary (K-T) extinction event.
Jean Baptiste Lamarck (1744-1829) • Established the field of invertebrate zoology. • Proposed a theory to account for variation in species, and hence, for evolution. • His theory of inherited characteristics was wrong but Darwin credited Lamarck as having been the first to assert that laws govern the diversity of nature.
Malthus and Darwin • Thomas Malthus (1766-1834). • In his book, Essay on the Principle of Population as it affects the future improvement of society (1798), he proposed that resources grow arith-metically, while population grows geometrically.
Malthus and Darwin • Malthus turned out to be wrong, but his insight about the struggle for resources across generations gave Darwin the idea for natural selection.
“In October 1838 … fifteen months after I had begun my systematic inquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from long- continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The results of this would be the formation of a new species. Here, then I had at last got a theory by which to work“ (Darwin 1876).
Charles Lyell (1797-1875) • Principles of Geology: being an attempt to explain the former changes of the earth's surface, by reference to causes now in operation, (1830-1833). • The principle of uniformitariansim – that the forces shaping the Earth today were the same from the beginning of time.
Darwin was helped by Lyell's observations about the age of fossils in developing the reproductive advantage theory of biological evolution.
Darwin and Wallace • Charles Darwin (1809-1882) Origin of Species by means of natural selection, or, The preservation of favoured races in the struggle for life (1859). • Alfred Russel Wallace (1823–1913) was in Malaysia, writing papers offering the same theory of evolution that Darwin was developing. • Darwin published first.
Darwin’s Breakthrough • Here is the famous passage from p. 64 of the 1859 edition: • “As more individuals are produced than can possibly survive, there must in every case be a struggle for existence, either one individual with another of the same species, or with the individuals of distinct species, or with the physical conditions of life.”
Gregor Mendel (1822-1884) • Versuche über Pflanzenhybiden (1866) • He planted a peculiar variety of ornamental plant at a monastery next to a typical specimen. • His idea was to test directly Lamarck’s theory. • The traits of all offspring conformed to those of the parent generation. • And of course, there were Mendel’s peas.
The First Primates • The Earth is about 4.5 billion years old. • Life appears at the end of the Precambrian, ~540 million years ago. • The Paleocene begins about 65 million years ago, with the disappearance of the dinosaurs, the rise of mammals and the development of the first primates.
Mammalian Traits • Distinctive mammalian traits include: • constant body temperature • postpartum development of helpless offspring • internal reproduction and fertilization • greater reliance on learned behavior
More Reliance on the Brain • Cerebrum of more importance. • In humans, the cortex is convoluted, like a wound coil, with specialized areas: • frontal lobe for choice and decisions • lower parietal lobe for associations and sensory data • temporal lobe for memory • lower frontal lobe for motor speech • occipital lobe for visual acuity
Nonhuman Primates • Linneaus identified primates as a separate family, with four genera: • Homo, Simia, Lemur, and Vespertilio. • Pan named in 1816; Gorilla in 1847. • In 1863, Thomas Huxley’s book, Man’s Place in Nature contained a conclusion about the close relationship between African apes and modern humans.
Nails, claws, and trees • Primates are mammals that climb by grasping – nails, not claws – the evolutionary correlate of arboreal adaptation, along with stereoscopic vision, a further increase in brain size, and a shortened snout. • Remember: teleological explanations are not assumed.
Prosimians • Two suborders: Prosimians and Anthropoids • Prosimians include the lorises, tarsiers and lemurs of Asia and Africa. • The special case of Madagascar. See Kottak’s discussion of this. • 65 mya
Anthropoids • 40 mya – anthropoids have bigger brains, relative to body size than the prosimians, a shorter snout, and front-facing eyes enclosed in bone. • Two types: catarrhines (Old World monkeys and apes) and platyrrhines (New World monkeys) separated 35mya in the Oligocene.
Catarrhines and the Hominoids • The catarrhines include circopithecoids and the colobines, as well as the hominoids. • The hominoids include the hylobates, the pongids, the genus Pan, and the hominids. • There is only one species of hominid today, H. sapiens sapiens.
Cercopithecines • Cercopithecines (Old World monkeys) have smaller brains relative to body size than hominoids (apes and humans). • Cercopithecines’ molars are bilophodont while those of the hominoids have several cusps. • Cercopithecoids have tails. Hominoids have no tails. • Prehensile tails are found only in New World monkeys.
Baboons • Baboons are the largest of the monkeys. • Sexual dimorphism: males reach 35kg, females reach 17kg • Baboons: terrestrial, live on the open savannah, frugiverous and herbivorous. • They do eat a little meat, but this feature is more important for the hominoids, especially Pan.
Hominoids and Hominids • Three families within the superfamily: • The hylobates include the gibbon and siamang of Southeast Asia. • Brachiation • Orangutans reach 80kg (males), 40kg for females • The pongids include the chimps, gorillas, and bonobos. • Hominids are us.
Chimps and Gorillas • Chimps spend their days on the ground and their nights in trees and live in communities of 40-60. • Gorillas reach 160kg (males), 80kg for females. • Gorillas are herbivorous and sleep on the ground. They are at the top of the food chain and have no predators – except us.
Chimps and Humans • Anatomical morphological data show the close relationship. • Immunological reactions, amino acid sequences, and DNA maps show close association among the chimp, gorilla, and human. • Best current estimate: humans split from the line leading to chimps and gorillas between 5-8 mya ago.
Summing up • H. sapiens is some ways like all other animals, and in some ways unique. • We share traits with all vertebrates – a spinal column – and we share traits with all mammals – constant body temp, for example – and we share traits with all primates, our closest relatives.
The traits we share with all primates are: • prehensile hands • mobility of arms through the shoulder • stereoscopic color vision • a small number of offspring born at one time, a long period of dependency and learning • very large brains, relative to body size • social organization.
As we get closer to humans in terms of DNA, we also share increased intelligence and increased social life. • A distinctive feature of humans is our nearly complete dependence on learning. • This implies a lot of social organization, and the use of tools, language, and culture.
Fossil Primates • Oligocene anthropoids – Aegyptopithecus (33mya) had the 2-1-2-3 dental formula. • Early Miocene (from 23–16mya): Proconsul was probably the last common ancestor of the hominoids.
Middle Miocene Apes • 16–10mya • Ramapithecus (14mya) in Asia and Africa • Drypopithecus (Europe) • Sivapithecus (India) • Kenyapithecus (East Africa) • Direct ancestors?
Late Miocene Apes 10–5 mya • The emergence of the hominids at the end of the Miocene and beginning of the Pliocene. • Ouranopithecus and Oreopithecus (Europe) and possible bipedalism. • Possible return migration to Africa from Europe during the late Miocene.
Differentiation of Primates in Africa • Mid-Miocene, 16mya, the forests that dominate Africa recede and the savannas open. • This favored the differentiation of primates into arboreal and terrestrial groups.
Theories for Differentiation • Freeing hands (hunting, safety) • Tall grass (seeing predators) • Sharing food between males and females left females sedentary • Using tools to capture food and as weapons allows hunting by otherwise puny animals • Note use by contemporary chimps
Raymond Dart and the Taung Child • Dart was a primate paleontologist • Stone quarry near the Kalahari produced baboon fossils, 200 miles from Johannesburg • Crates arrive in 1924 and Dart takes 73 days to isolate the Taung Child’s skull.
Dart’s reaction … • “No diamond cutter ever worked more lovingly or with such care on a priceless jewel – nor, I am sure, with such inadequate tools. But on the 73rd day, Dec 23, the rock parted. I could view the face from the front, although the right side was still imbedded. The creature which had contained this massive brain was no giant anthropoid such as a gorilla. What emerged was a baby’s face, an infant with a full set of milk teeth and its permanent molars just in the process of erupting. I doubt if there was any parent prouder of his offspring than I was of my Taung baby on that Christmas.”
Australopithecus • Dart names it Australopithecus africanus, suggesting that it was an intermediate species between apes and humans. • Focus on the downward-facing foramen magnum
Robert Broom • It takes until 1936 until another similar fossil is found. • Two years later, in 1938, Broom discovers the Swartkrans site: 528 fossils of 60 individuals, over 14 years, plus 195 nonindigenous stones, some of which had been worked by human hands.
The Foramen Magnum • Dart and Broom were rejected – the prevailing view was that the brain had evolved first. • But there was that annoying fact of the downward facing foramen magnum • The idea of the primacy of post-cranial evolution eventually won out.
Two Australopithecines? • There were two kinds of Australopithecine, a gracile and a robust variety. • The graciles were earlier, which caused confusion at first, since robust meant primitive to many observers.
Hominid sequence I • Sahelanthropus • Ardipithecus ramidus • Australopithecus anamensis • Australopithecus afarensis • Australopithecus africanus Taung • Australopithecus robustus (P. robustus • Australopithecus boisei (P. boisei, Zinj)
Hominid sequence II • Homo habilis (P. rudolfensis) • Homo rudolfensis • Homo ergaster • Homo erectus Trinil (P. erectus) • Homo heidelbergensis Mauer • Homo rhodesiensis Kabwe • Homo neanderthalensis • Homo sapiens
The Miocene Fossil Gap Closes • Sahelanthropus tchadensis (Toumai) has a brain the size of a chimp’s, with a flat face. 6–7mya
Ramidus 1994 Ethiopia – slightly forward foramen magnum. Perhaps still partially arboreal Anamensis 1965, not identified, 1994 Lake Turkana. Nearly full skeleton shows full bipedalism
A. afarensis Afarensis – Afar region of Ethiopia. Lucy at Hadar. Some 40 individuals. 3.7–2.9mya The afarensis footprints – 75 feet, Laetoli, Tanzania. Strong arch, well-defined ball, straight big toe. Brain case of 415cc (compare to chimp and gorilla and modern human) Canine diastema and protruding incisors. Dentition of Miocene apes, but orthograde