F. Ayala Human Nature U.C. Irvine biologist Past President of AAAS Genetics, evolution, philosophy of science

In God’s Image We are like other apes We are unlike other apes Cultural as well as genetic inheritance Cultural evolution much faster Genes make us able to be ethical Culture (inc. religion) provides the code, norms

Hominid Species "Hominid" refers to members of the family Hominidae, which consists of all species on our side of the last common ancestor of humans and living apes. Hominids are included in the superfamily of all apes, the Hominoidea, the members of which are called hominoids.

Human phylogeny Diverged from chimp line 5-7 Mya By 1.8 Mya, Homo erectus Other, older hominids too: not all on lineage to Homo sapiens H. erectus spread outside Africa H. sapiens (archaic) ca. 400,000 years ago –no clear dividing line between late erectus and archaic sapiens H. sapeins neanderthalensis 200,000 years ago until 30-40,000 years ago - coexisted with H. sapiens. Mostly lived in cold climates. Buried their dead.

Homo sapiens sapiens (modern) First appear about 120,000 years ago. About 40,000 years ago, with Cro-Magnon culture, tool kits more sophisticated. Art, music. Within the last 100,000 years, trends towards smaller molars and decreased robustness continuing. –The face, jaw and teeth of Mesolithic humans (about 10,000 years ago) are about 10% more robust than ours. –Upper Paleolithic humans (about 30,000 years ago) are about 20 to 30% more robust than us.

How did H. sapiens arise? Multiregional hypothesis: occurred in various places Others think only happened once, in Africa –Ayala favors this view “Mitochondrial Eve” a gene geneology How small a bottleneck ? - at least several thousand individuals, not just two or a few

How are humans unique today? Anatomy –Erect posture, bipedal gait (came first) –Large brain (came later) –Brain organization also different (large cortex)

How are humans unique today? Behavior –Abstract thinking –Subtle expression of emotions –Symbolic (creative) language –Awareness of self, death –Science, humanities, ethics, religion

Cultural inheritance and evolution Different than biological evolution –More rapid –Can be directed Transmission of experience to next generation –Fire –Clothing –Tools –Transportation

What about ethics? Like language... Capacity, proclivity, is biological Moral norms, codes, however, are cultural

What does he mean by ethical capacity? Can anticipate consequences Can make value judgements Can choose between alternatives

Ayala rejects sociobiologists thesis Grants a correspondence, isomorphism, in consequences of moral behavior. Rejects thesis that the causes of human moral behavior are products of natural selection.

V. Elving Anderson Clinical, medical, human geneticist Past President of Sigma Xi Gene mapping research

From puppet to Prometheus Old genetic fatalism replaced by... New fears of “playing God”

What’s special about human genes? No one “human” gene or genes 98.4% genetic identity with chimps Allelelic variation and expression of some genes may be different from that in non- human primates

Development of human behavior Most is plastic, not stereotyped or instinctive Inherit a range of reaction, behavior, based on genes Environment and experience determine actual behavior within that range

Twin studies show correlations Highest for physical traits Mental ability next Personality next Interests least correlated

Some basics of gene expression Genes act together in networks Genes interact with environment, experience Gene action on behavior is indirect

What about IQ ? 0.15 attributable to non-shared experiences Shared experience component declines with age –0.30 from 4-20 years of age –zero among adult twins Genetic component rises in replacement –0.51 from 4-20 years of age –0.80 among adult twins