Human Evolution

Human Evolution I. What are humans related to?

Human Evolution I. What are humans related to? - Morphologically similar to apes - hands, binocular vision (Primates) No tail

Human Evolution I. What are humans related to? Apes II. How do we differ?

Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect)

Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect) - Behaviorally (intelligence and learning)

Human Evolution I. What are humans related to? Apes II. How do we differ? - Behaviorally (walk erect) - Behaviorally (intelligence and learning) - Morphologically, humans have: - larger head/body ratio - smaller jaw/head ratio - shorter arms/body ratio - less hair

Human Evolution I. What are humans related to? Apes II. How do we differ? - Morphologically Human Chimp Gorilla Orangutan Gibbon

Human Evolution I. What are humans related to? Apes II. How do we differ? - Genetically: Big Surprize! Human Chimp Gorilla Orangutan Gibbon

Human Evolution I. What are humans related to? Apes II. How do we differ? - Genetically: Big Surprize! Human Chimp Gorilla Orangutan Gibbon < 1% difference in gene sequence

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? Can this 1% difference account for the dramatic behavioral and morphological differences we see?

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? Can this 1% difference account for the dramatic behavioral and morphological differences we see? Yes, some genes have big effects. These are regulatory genes, acting during development. They influence the expression of lots of other genes…

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? Can this 1% difference account for the dramatic behavioral and morphological differences we see? Yes, some genes have big effects. These are regulatory genes, acting during development. They influence the expression of lots of other genes… - Can we test this hypothesis? Do the differences correlate with developmental effects?

Yes. All differences correlate with developmental differences between juvenile primates and adults… Juveniles Adults Larger Head/body ratio smaller Smaller jaw/head ratio larger Shorter limb/body ratio longer Less hair more hair Better learning poorer learning

Yes. All differences correlate with developmental differences between juvenile primates and adults… Juveniles Adults Larger Head/body ratio smaller Smaller jaw/head ratio larger Shorter limb/body ratio longer

Yes. All differences correlate with developmental differences between juvenile primates and adults… Juveniles Adults Larger Head/body ratio smaller Smaller jaw/head ratio larger Shorter limb/body ratio longer Less hair more hair Better learning poorer learning Human-like Ape-like

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? Can this 1% difference account for the dramatic behavioral and morphological differences we see? Yes, if the small change is in developmental genes, they can have BIG effects…humans might be a type of ape that didn’t grow up… The ways we differ supports this hypothesis…

Yes, if the small change is in developmental genes, they can have BIG effects…humans might be a type of ape that didn’t grow up… Small changes in development, especially if they occur early in development, can result in big effects. Human Chimp Primate developmental trajectory

What are some of these genetic differences? The HAR1 RNA molecule. - not a coding RNA; probably regulatory Beniaminov A, Westhof E, and Krol A. 2008. Distinctive structures between chimpanzee and human in a brain noncoding RNA. RNA 14:1270-1275.

What are some of these genetic differences? The HAR1 RNA molecule. - not a coding RNA; probably regulatory - nearby genes associated with transcriptional regulation and neurodevelopment are upregulated in humans. Beniaminov A, Westhof E, and Krol A. 2008. Distinctive structures between chimpanzee and human in a brain noncoding RNA. RNA 14:1270-1275.

What are some of these genetic differences? The HAR1 RNA molecule. - not a coding RNA; probably regulatory - nearby genes associated with transcriptional regulation and neurodevelopment are upregulated in humans. - only 2 changes in sequence between chicks and chimps; 18 between chimps and humans… “HAR” stands for “human accelerated region” – changing more rapidly than drift can explain… why? Selection. Beniaminov A, Westhof E, and Krol A. 2008. Distinctive structures between chimpanzee and human in a brain noncoding RNA. RNA 14:1270-1275.

What are some of these genetic differences? The HAR1 RNA molecule. - not a coding RNA; probably regulatory - nearby genes associated with transcriptional regulation and neurodevelopment are upregulated in humans. - only 2 changes in sequence between chicks and chimps; 18 between chimps and humans… “HAR” stands for “human accelerated region” – changing more rapidly than drift can explain… why? Selection. Changes result in a profound change in RNA structure and, presumably, binding efficiency. Beniaminov A, Westhof E, and Krol A. 2008. Distinctive structures between chimpanzee and human in a brain noncoding RNA. RNA 14:1270-1275.

Two distinct experimentally supported secondary structure models for HAR1 RNAs. HUMAN CHIMP Two distinct experimentally supported secondary structure models for HAR1 RNAs. (A) The cloverleaf-like model of the human HAR1 RNA. (B) The chimpanzee HAR1 RNA adopts a hairpin structure. The length and thickness of the symbols represent the intensity of the cleavages. Bases reactive to DMS or CMCT under native conditions are circled; weak reactivities are depicted by dotted circles. Bases modified by CMCT under semidenaturing conditions only are displayed with a green background. H, helix; IL, internal loop; L, loop. Beniaminov A et al. RNA 2008;14:1270-1275 Copyright © 2008 RNA Society

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? IV. Are there common ancestors?

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? IV. Are there common ancestors? Yes. Just where evolution predicts they should be (After other monkeys and apes, before humans and existing apes).

Molecular clock analyses

12-13 mya: oldest ‘great ape’ Science, Nov 19, 2004 Pierolapithecus catalaunicus 12-13 mya: oldest ‘great ape’

‘apes’ – no tail

V. Are there common ancestors? - Fossil and genetic analysis independently predict a common ancestor between humans and chimps lived 5-8 million years ago. Chimpanzee Human Homo sapiens

V. Are there common ancestors? - Fossil and genetic analysis independently predicted a common ancestor between humans and chimps lived 5-8 million years ago. Chimpanzee Human Homo sapiens Sahelanthropus tchadensis* – discovered in Chad in 2001. Dates to 6-7 mya. Only a skull. Is it on the human line? Is it bipedal? Foramen magnum perhaps suggestive of bipedality. Primitive traits, as a common ancestor might have. (* know these)

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? IV. Are there common ancestors? V. Are there intermediate links to modern humans?

V. Are there intermediate links to modern humans? yes - with a divergence of two types of hominids around 2 mya

V. Are there intermediate links to modern humans? - with a divergence of two types of hominids around 2 mya “slender” species

V. Are there intermediate links to modern humans? - with a divergence of two types of hominids around 2 mya “slender” species “robust” species

V. Are there intermediate links to modern humans? - with a divergence of two types of hominids around 2 mya Ardipithicines: Primitive, bipedal species

Orrorin tugenensis. : 5. 6-6. 2 mya Orrorin tugenensis*: 5.6-6.2 mya. Discovered in 2000 by Brigitte Senut, Tugen Hills, Kenya. Processes on femus suggest bipedality in this forest-dwelling species. * Know these ones

Tugen Hills, Kenya

(Cerling, et al. 2011)

Ardipithecus kadabba: 5. 6 mya Ardipithecus kadabba: 5.6 mya. Discovered in 2004 by Haile-Sailasse, Gen Suwa, and Tim White, Middle Awash, Ethiopia. Initially thought to be chronospecies of A. ramidus, tooth size in recent fossils suggested a new species.

Ardipithecus ramidus. : 4. 3-4. 5 mya Ardipithecus ramidus*: 4.3-4.5 mya. Discovered in 1994 by Haile-Sailasse, Suwa, and White, Middle Awash, Ethiopia. with the most complete fossils were not described until 2009. Arboreal, but facultatively bipedal. Grasping toes. video

Tugen Hills, Kenya

V. Are there intermediate links to modern humans? - with a divergence of two types of hominids around 2 mya Australopithecine Radiation

Australopithecus anamensis: 3. 9-4. 4 mya Australopithecus anamensis: 3.9-4.4 mya. About 100 fossils, from an estimated 20 individuals; all from the Lake Turkana region of east Africa. Found in 1965, 1987, 1995, and 2006, it was only in 1995 when Meave Leakey distinguished it from other Australopithecine species. Probably the direct ancestor of A. afarensis. Dr. Meave Leakey is spouse of Dr. Richard Leakey, son of Louis and Mary Leakey – discoverers of several ancient hominids at Olduvai Gorge. Unambiguous biped

Australopithecus afarensis. : 2. 8-3. 9 mya Australopithecus afarensis*: 2.8-3.9 mya. A femur discovered in 1973 by Donald Johansson suggested an upright gait, confirmed by his discovery in 1974 of the ‘Lucy” specimen. Also, the Laetoli prints (found by Mary Leakey) were probably made by A. afarensis, and in 2006, a juvenile A. afaresis was found.

And, as we’ve discussed, Australopithecus afarensis walked erect. video

And, as we’ve discussed, Australopithecus afarensis walked erect.

A. Afarensis prints at Laetoli, approximately 3 A. Afarensis prints at Laetoli, approximately 3.56 myr, were made by an obligate biped: - heel strike. - Lateral transmission of force from the heel to the base of the lateral metatarsal. - A well-developed medial longitudinal arch. - Adducted big toe, in front of the ball of the foot and parallel to the other digits. - A deep impression for the big toe commensurate with toe-off.

Australopithecus bahrelghazali: 3 Australopithecus bahrelghazali: 3.6 mya; discovered in Chad in 1993 by Michel Brunet – who won’t release it for others to study. Most paleontologists suggest it is within the range of variation for A. afarensis. First australopithecine outside of east Africa.

Kenyanthropus platyops: 3. 2-3 Kenyanthropus platyops: 3.2-3.5 mya – Discovered by Meave Leakey’s team at Lake Turkana; most dispute it warrants another genus, and some even include it in A. afarensis.

Australopithecus africanus Australopithecus africanus*: 2-3 mya, discovered by Raymond Dart in South Africa in 1924 – the ‘Taung child’. Then, in 1947, Robert Broom found a skull he classified as Plesianthropus, but was grouped with A. africanus. Seems a precursor to Paranthropus lineage.

Tugen Hills, Kenya

Australopithecus garhi: 2. 5-2 Australopithecus garhi: 2.5-2.6 mya; discovered by Asfaw and White in 1996, Middle Awash, Ethiopia. but the skull below was discovered by Haile-Selasse in 1997. The tooth morphology is a bit different from A. afarensis and A. africanus, being much larger than even the robust forms. There are associated stone tools, and long femur suggests longer stride.

Australopithecus sebida. : 1 Australopithecus sebida*: 1.9 mya, describe in 2010 by LE Berger; it has many characteristics like A. africanus, but also similar to genus Homo. Six almost complete skeletons from South Africa.

V. Are there intermediate links to modern humans? - with a divergence of two types of hominids around 2 mya Paranthropus Clade

Paranthropus. aethiopicus: 2. 5-2 Paranthropus* aethiopicus: 2.5-2.7 mya, discovered by Alan Walker and Richard Leakey, Turkana Basin. The “black skull” is one of the most imposing hominid fossils there is! Aside from the high cheekbones and the sagittal crest, it has similar proportions to A. afarensis and is probably a direct descendant. It probably gave rise to the “robust” lineage of Paranthropus. *know genus

Paranthropus boisei: 1. 2-2. 6 mya Paranthropus boisei: 1.2-2.6 mya. Discovered by Mary Leakey in Olduvai Gorge in 1959, it was originally classified as Zinjanthropus and nicknamed “Zinj” or “nutcracker man” because of the large grinding molars.

Paranthropus robustus: 1. 2-2. 0 mya Paranthropus robustus: 1.2-2.0 mya. Discovered in South Africa in 1938 by Robert Broom.

V. Are there intermediate links to modern humans? - with a divergence of two types of hominids around 2 mya Genus Homo

Homo habilis*: 1.4-2.3 mya, discovered by Louis and Mary Leakey, Olduvai Gorge, in association with stone tools. “Handy man”. Ultimately, tools dated much earlier. Longer arms and smaller brain than other members of the genus.

Tugen Hills, Kenya

Homo rudolphensis: 1.9 mya; Discovered by Richard and Meave Leakey’s team. Different from H. habilis, yet a contemporary. One really good skull and some other bones. Significantly larger braincase than H. habilis. Either may be ancestral to recent Homo.

Homo erectus*: 0.2-1.8 mya; originating in Africa, but then leaving for Asia (Dmanisi, Peking and Java Man). Discovered in Java by Eugene Dubois in 1891. Certainly one of the most successful hominid species in history; perhaps lasting as relictual species on islands in Indonesia…

Homo georgicus: 1.7 mya; the oldest hominid fossils found outside of Africa – found in Dmanisi, Georgia, in 1999. Now typically classified as H. erectus.

Homo floresiensis*: 94,000-13,000 years, discovered by Mike Mormood on the island of Flores. Shoulder anatomy is reminiscent of H. erectus, but could be an allometeric function of the small size (3 ft).

Homo ergaster : 1.3-1.8 mya, the most complete fossil hominid skeleton was discovered in 1984 by Alan Walker who called it “Turkana Boy”. Some consider this species intermediate to H. habilis and H. heidelbergensis/H. sapiens, leaving H. erectus as a distinct Asian offshoot of the main line to H. sapiens. However, most paleontologists suggest that this is an ancestral African population of H. erectus, and ancestral to more recent Homo species.

Homo heidelbergensis*: 125-800,000 in Europe and Africa; ancestral to H. neaderthalensis and H. sapiens; may have buried their dead. First species to colonize cold habitats, and northern populations show a squat body perhaps associated with climate. Seem to be a very graded melding of H. erectus and H. neanderthalensis traits.

Homo rhodesiensis: 125-300,000; may be H Homo rhodesiensis: 125-300,000; may be H. heidelbergensis or intermediate to it and H. sapiens. Homo antecessor: 800,000-1.2 mya; fossils from 20 individuals found in Spain in 1994-5; may be H. heidelbergensis or an intermediate between it and H. erectus. Homo cepranensis: 350,000-500,000 years old; discovered by Italo Biddittu in 1994 in Italy. It is just a skull cap, but seems to be intermediate between H. erectus and H. heidelbergensis.

Homo neaderthalensis. : 30,000-150,000; first discovered in 1829 Homo neaderthalensis*: 30,000-150,000; first discovered in 1829. Descended from H. heidelbergensis. Homo sapiens* idaltu: 160,000 – oldest Homo sapiens fossil – found in Africa in 2003… Afar valley.

The enigmatic Denisovans A finger bone and tooth discovered in a cave in 2011, with enough DNA to do a complete gene sequence.

The enigmatic Denisovans

The enigmatic Denisovans 800,000 years ago

Human Evolution I. What are humans related to? Apes II. How do we differ? III. Resolution? IV. Are there common ancestors? V. Are there intermediate links to modern humans? VI. And what of our species?

- From Africa 200,000 years ago (earliest fossils, genetic variability, etc.); hunter gatherers. (Brazil) (Brazil)

- From Africa 200,000 years ago (earliest fossils, genetic variability, etc.); hunter gatherers.

Genetic diversity in Homo sapiens is inversely correlated to distance from Ethiopia (AA = Addis ababa,Capitol)

- From Africa 200,000 years ago (earliest fossils, genetic variability, etc.); hunter gatherers. - Earliest Art – Cave Paintings in South Sulawesi, Indonesia (35,000 – 40,000)) Pettakere Cave

- From Africa 200,000 years ago (earliest fossils, genetic variability, etc.); hunter gatherers. - Earliest Art – Cave Paintings in Chauvet, France (30-32,000)

- From Africa 200,000 years ago (earliest fossils, genetic variability, etc.); hunter gatherers. - Cave Art about 30,000 years ago - 14,000 years ago, bands settled in different areas of the globe and began to grow local crops. First Agricultural Revolution….

Fertile Crescent Eastern U. S. China Sahel? Mesoamerica New Guinea Where and when: Fertile Crescent Eastern U. S. China Sahel? Mesoamerica New Guinea Amazon? West Africa? Ethiopia? Andes

And Now… The Anthropocene:- 14,000 years to present. Score of human impact due to land transformation, soil, water, and air quality. (Each biome has it’s own scale, however, so they are not explicitly comparable).

Adaptations to Local Environments:

Genetic variation in Europe correlates remarkably well with geography

Adaptations to Local Environments: LCT – locus coding for lactase production - mammals shut down lactase production after weaning - strong selective sweep in Europeans and Africans that drink milk as adults - European sequences: ~ 9000 years old but show spread about ~4000 ya - African sequences ~ 5000 ya, consistent with spread of cattle - convergent evolution of different variants with same effects Lactase Persistence (activity into adulthood)

Adaptations to Local Environments: LCT – locus coding for lactase production Adaptations to the Arctic - Inuit of Alaska, Canada, and Greenland have diet rich in polyunsaturated Omega-3 fatty acids - have specialized gene cluster encoding fatty acid desaturase (FADS). Two variants found in the Inuit are associated with short stature; also found in European populations but at very low frequencies.

Adaptations to Local Environments: LCT – locus coding for lactase production Adaptations to the Arctic 3. Adaptations to Tropical rainforests - short stature: reduced resources, heat stress and SA/V ratios, trade-offs with early onset of reproduction, resistance to endemic pathogens (malaria)