Human Evolution Mader: Biology 8th Ed.

Classification of Modern Humans Kingdom:   Animalia Phylum:   Chordata Class:   Mammalia Order:   Primates Family:   Hominidae Genus:   Homo Species:   sapiens Mader: Biology 8th Ed.

Describe the major anatomical features that define humans as primates. IB Learning Objective Describe the major anatomical features that define humans as primates. Mader: Biology 8th Ed.

Characteristics we share with primates Humans retain pentadactyl limbs with five digits and marked mobility of digits All primates have grasping hands with long fingers and a separate opposable thumb Mader: Biology 8th Ed.

Characteristics we share with primates Hands/ Grasping Limbs – with long fingers and a separate opposable thumb Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Characteristics we share with primates Mobile arms with shoulder joints that allow us to move in three planes We are born to CLIMB! Mader: Biology 8th Ed.

The arrangement of bones at shoulder permits brachiation movement Limbs/ Mobile Arms The arrangement of bones at shoulder permits brachiation movement the bones of the shoulder girdle allow weight to be transferred via the arms Mader: Biology 8th Ed.

Characteristics we share with primates Developed upright walk and extensive head rotation Our skulls are modified for an upright posture Mader: Biology 8th Ed.

Characteristics we share with primates Unique Eyes Forward facing eyes on a flattened face Mader: Biology 8th Ed.

Characteristics we share with primates Developed unique eyes The eyes look forward with overlapping visual giving stereoscopic vision (depth persption Depth perception is an invaluable tool for animals that move quickly.  It allows them to judge the distances to important objects in their environments. For monkeys jumping from branch to branch high up in the canopies of forests, this is a matter of life and death.  Likewise, accurate depth perception is a critical capability for hunters who need to judge distances Mader: Biology 8th Ed.

Stereoscopic Vision Stereoscopic vision and resultant depth perception allows primates to make accurate judgments about distance and position of adjoining tree limbs. Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Characteristics we share with primates Reduction in nose and teeth Flattened noses decrease ability to smell Reduced in number of teeth Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Other Primate Characteristics Skull modified for upright posture Nails instead of claws. Single births Expanded, complex brain. Emphasis on learned behavior. Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

The unavoidable conclusion Humans evolved from other primate species. That is we share a common ancestor with other primates, i.e. chimpanzee. Mader: Biology 8th Ed.

From Apes to Humanity in 35 million years Anthropoids – Apes Earliest fossil 35 million years ago in Africa. Mader: Biology 8th Ed.

From Apes to Humanity in 35 million years Anthropoids – Apes Early anthropods were agile tree dwellers Important feature was brachiation of limbs that allowed them to swing between trees Mader: Biology 8th Ed.

From Apes to Humanity in 35 million years Anthropoids – Apes At the time of human and ape evolution the climate had periods of extreme environmental change. Environmental change was partially due to movements in the tectonic plates and thus the continents. Mader: Biology 8th Ed.

From Apes to Humanity in 35 million years Climate Change About 15 million years ago Africa collide with Eurasia. Mader: Biology 8th Ed.

From Apes to Humanity in 35 million years Climate Change As a consequence, the climate in Africa became drier and colder. Rainforest were the apes lived were reduced to isolated pockets. Large Savannahs spread over Africa Mader: Biology 8th Ed.

From Apes to Humanity in 35 million years Climate Change Many scientists believe that bipedalism (ability to walk upright) developed in the savanna about 5 Mya; Mader: Biology 8th Ed.

Discuss the anatomical features that enable bipedalism in humans. arches on feet; stronger bones in legs / stronger legs; longer legs; shorter arms; non-opposable big toe; foramen magnum further forward; knees closer together; wide pelvis; lumbar spine curved; larger muscles on legs;

Evidence of Bipedalism fossil footprints found (at Laetoli) 3.6 Mya; anatomy of hominids suggests bipedality at 4.4 Mya; bipedality possibly associated with a change in habitat and climate Mader: Biology 8th Ed.

Advantages of bipedalism Advantages of walking upright Freed hands up to obtain or carry food Hands are free to carry offspring. Mader: Biology 8th Ed.

Advantages of bipedalism Advantages of walking upright bipedality provides greater field of view for foraging / detecting predators; Mader: Biology 8th Ed.

More advantages of being bipedal Thermoregulation: Smaller surface area presented to the sun at midday (60%) Greater air flow across body when it is lift off the ground Mader: Biology 8th Ed.

Trends in Hominid Fossils Hominids are members of the family Hominidae. A notable feature of this family is the ability to walk on two legs, called bipedalism. Homo sapiens is only surviving member of the Hominidae family, but in the past several species co-existed, example Homo neaderthalensis. Mader: Biology 8th Ed.

IB Learning Objectives Outline the trends illustrated by the fossils of Ardipithecus ramidus, Australopithecus including afarensis and A. africanus. Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Trends in Hominid Fossils Many hominid fossils have bee found, dated and assigned to species. These fossils show the following evolutionary trends Increasing adaptation to bipedalism Increasing brain size relative to body size Mader: Biology 8th Ed.

Location of hominid fossils Hominids genus/ species fossil location Ardipithecus – Ethiopia Australopithecus and Homo Habilis – Southern or Eastern Africa Homo Erectus – Eastern Africa & Asia Homo neanderthalensis found in Western Asia & Europe Homo sapiens many parts of the World. Mader: Biology 8th Ed.

Only fragments of skulls and other bones have been found Ardipithecus ramidus Ardipithecus ramidus 4.4 Million years ago Only fragments of skulls and other bones have been found They show intermediate characteristics between chimpanzees & Australopithecus Mader: Biology 8th Ed.

Ardipithecus ramidus Ardipithecus ramidus characteristics Teeth Small number of larger molars like a chimps Incisors slightly smaller than those of a chimp Canines blunt & projecting less that those of a chimp Mader: Biology 8th Ed.

Ardipithecus ramidus Ardipithecus ramidus characteristics Skull & Bipedalism Foraman magnum (hole through which the spinal cord enters the skull) further forward than in chimps suggesting partially Bipedalism Mader: Biology 8th Ed.

Australopithecines It is possible that one of the australopithecines that evolved and diversified in Africa 4 mya is a direct ancestor of humans. Southern Africa Australopithecus africanus Eastern Africa Australopithecus afarensis Mader: Biology 8th Ed.

Australopithecines – Southern Apes Existed 5 to 1.5 mya Lucy – Australipithecus afarensis - 3 mya Lucy walked upright ( bipedalism) Evidence to support the above idea footsteps in volcanic ash – known as the Laetoli Ash. The Laetoli Ash was dated using the radioactive method…. Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Laetoli Ash. Mader: Biology 8th Ed.

Australopithecus afarensis 4- 2.5 million years ago. Tall lower jaw Fairly large molars Projecting face. Brain size 380- 430 cc Mader: Biology 8th Ed.

Autralopithecus africanus 3-2.5 million years ago Tall thick lower jaw Large molars Projecting face Bony strut Brain Size 435 – 530 cc Mader: Biology 8th Ed.

Outline the trends illustrated by the fossils of Australopithecus afarensis. (3 points) A. afarensis had traits that indicated bipedality such as a non opposable big toe, a broad pelvis , a more vertical posture and a skull on top of vertebrae; A. afarensis also had short legs indicating bipedality; A. afarensis curved finger bones; which indicated it was still arboreal (living in trees); A. afarensis had conical thorax; indicating vegetarian diet; A. afarensis dentition (teeth) more like a chimp than modern humans for example they had larger canines and parallel molars; n. the part of the human torso between the neck and the diaphragm or the corresponding part in other vertebrates Mader: Biology 8th Ed.

First hominids to use tools Homo habilis Homo habilis – 2.4 to 1.5 mya Different from Australopithecines by having light cranial bones and enhanced cranial capacity. First hominids to use tools Mader: Biology 8th Ed.

Bigger brain size relative to body size Brain Size was 600cc Homo habilis – Flatter face Large molars Bigger brain size relative to body size Brain Size was 600cc Mader: Biology 8th Ed.

Explain why the approximate date and distribution of H Explain why the approximate date and distribution of H. habilis are uncertain.(3 pts) Homo habilis existed about 2 (±0.5) million years ago in (sub-Saharan) Africa; Dates have high uncertainty because: fossils lacking or not in good form; soft parts do not fossilize; interbreeding of between H. habilis and other hominid species species may have lead to a mixture of traits and thus miss identification by scientist; H. habilis might have migrated to other areas ; Scientists have different views about when and where H. habilis lived; Fossil dating method not totally accurate; Mader: Biology 8th Ed.

First hominid to migrate to other places and use fire Homo erectus Homo erectus – 1.7 t0 1.8 mya First hominid to migrate to other places and use fire Large body and brain. Because of brain size and shape probably developed language. Brain size 1000cc Mader: Biology 8th Ed.

Bigger brain size relative to body size Homo erectus Homo erectus – Smaller molars Receding forehead A large brow-ridge Smaller jaw Bigger brain size relative to body size Mader: Biology 8th Ed.

Larger brain and flatter face than Homo habilis. Homo erectus Larger brain and flatter face than Homo habilis. Much taller than previous hominids. Mader: Biology 8th Ed.

Early Humans Had large brains and busy hands Homo erectus – Fossils have been found all over Europe, Asia, and Africa. Steinheim Germany (0.25 mya) Sale, Morocco (0.25 mya) Petralona, Greece (0.3 mya) Choukoutein, China (Peking Man) (0.5 mya) Swartkans, South Africa (1 mya) Mader: Biology 8th Ed.

Where Homo erectus fossils have been found. Mader: Biology 8th Ed.

Homo neanderthalensis 200,000- 30,000 years ago Existed at the same time as Homo sapiens Lower forehead Smaller brow ridge Smaller molars Smaller jaw Brain Size 1600 cc Mader: Biology 8th Ed.

An example of this is H. neanderthalensis and H. sapiens. IB LEARNING OBJECTIVE State that, at various stages in hominid evolution, several species may have coexisted. An example of this is H. neanderthalensis and H. sapiens. Mader: Biology 8th Ed.

Homo Sapiens 140,000 years ago High forehead Very small jaw Small molars Flat face No brow ridges Brain size 1300 cc Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

IB Learning Objective Outline the trends illustrated by the fossils of including H. habilis, H. erectus, H. neanderthalensis and H. sapiens. Mader: Biology 8th Ed.

IB LEARNING OBJECTIVE Knowledge of approximate dates and distribution of the named species is expected Ardipithecus ramidus, Australopithecus afarensis A. africanus. H. habilis, H. erectus, H. neanderthalensis H. sapiens. Mader: Biology 8th Ed.

The Origin of Modern Humans Homo sapiens – Arose in Africa about 140,000 ya Evidence from Mitochondrial DNA indicate that today’s population are related to an African human ancestor. Mader: Biology 8th Ed.

More evidence analysis of Y-chromosome suggest modern humans are descendents of African-inhabiting ancestors at least 150,000 ya. Mader: Biology 8th Ed.

The Origin of Modern Humans Homo neanderthalensis– Arose in Central and Western Europe about 250,000 ya Went extinct between 45,000 and 32,000ya Mader: Biology 8th Ed.

The Origin of Modern Humans Homo neanderthalensis– Brain size was bigger than modern humans Heavier & more muscular than modern humans Existed at the same time and place as modern humans. Why did they go extinct? Mader: Biology 8th Ed.

Homo neanderthalensis Mader: Biology 8th Ed.

Human Evolution Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Evolution of the modern human brain The brains of early hominids (Australopithecus) were only slightly larger relative to body size than modern apes. The teeth and jaws of early hominids suggest a mainly vegetarian diet. Mader: Biology 8th Ed.

Human Evolution Tutorials/ Animations https://www.23andme.com/gen101/prehistory/prologue/ http://www.becominghuman.org/ http://www.smithsonianmag.com/ist/?next=/science-nature/The-Top-Ten-Daily-Consequences-of-Having-Evolved.html Mader: Biology 8th Ed.

IB LEARINING OBJECTIVE Discuss the correlation between the change in diet and increase in brain size during hominid evolution. Mader: Biology 8th Ed.

Evolution of the modern human brain About 2.5 million years ago Africa became cooler and drier. Savannah and grassland replaced the forest. This change in climate is thought to have prompted the evolution of the first Homo . Mader: Biology 8th Ed.

Evolution of the modern human brain The Homo population could no longer hide in tree and there was less vegetation to feed on. Homo could make and use tools to hunt other animals and defend themselves from predation survived. This change in diet from a vegetarian based diet to a meat based diet corresponds to a rapid change in brain size. WHY? Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Brains are metabolically expensive. Diet and Brain Size Brains are metabolically expensive. Brains make up 2% of our body mass, but respire 20% of our energy budget. Human brain is 3X the size of apes’. This means a requirement for human evolution was a reliable diet of protein and fat. Scientists believe that early humans ate a lot of bone marrow discarded from larger predators. Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

The correlation between brain size and diet are explained in two ways: Diet and Brain Size The correlation between brain size and diet are explained in two ways: Eating meat increases the supply of protein, fat, and energy in the diet, making it possible for the growth of larger brains. Catching and killing prey on the savannas is more difficult that gathering plants, so natural selection favoured hominids with larger brains and greater intelligence. Mader: Biology 8th Ed.

large brain size correlates with language; Outline consequences of an increase in brain size for the Homo lineage. large brain size correlates with language; large brain correlates with improvements in tool-making; improved tools allow more nutritious diets for further brain development; increased brain size leads to rituals / burying the dead; excellent eye-hand coordination; increased brain size leads to written history / cave art / symbolic thought;

Large brain size lead to cultural evolution Mader: Biology 8th Ed.

Distinguish between genetic and cultural evolution. IB LEARNING OBJECTIVE Distinguish between genetic and cultural evolution. Mader: Biology 8th Ed.

Genetic vs. Cultural Evolution

Genetic Evolution Refers to changes in allele frequency in a population.

Genetic Evolution Changes in allele frequency are due two main factors: Genetic Variation in phenotypes Some phenotypes are better able to survive and reproduce than others

Cultural Evolution Refers to the development of customs, civilization and achievements of people.

Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

IB LEARNING OBJECTIVE Discuss the relative importance of genetic and cultural evolution in the recent evolution of humans. Mader: Biology 8th Ed.

Important Developments in cultural Evolution Extension of the Period of parental care The Development of Language The development of tool technology

Important Developments in cultural Evolution Extension of the Period of parental care Delayed onset of puberty Resulting long childhood, when the next generation of a population are trained and schooled as they develop essential survival skills.

The Development of Language Structures necessary for elaborate vocal communication was found in early hominids: Fossilized braincase show that areas of the brain where language is constructed was enlarged. Positions of Vocal folds in the neck high positioned larynx

Important Developments in cultural Evolution The Development of Language Verbal communication advantages: Passing on new ideas What else can you think of that would be an advantage of having a language?

Important Developments in cultural Evolution The development of tool technology About 35000 years ago modern humans had spectacular advances: bones, antlers and stones were modified to make blades, chisels, drills, arrowheads, and barbs

Important Developments in cultural Evolution The development of tool technology Artistic skills developed. Drawing dating to 25000 to 10000 years ago showing contemporary animals in scientific detail.

Relative importance of genetic and cultural evolution Human cultural evolution human agricultural and other technologies has allowed humans to significantly change their environment.

Relative importance of genetic and cultural evolution Human cultural evolution Enlarged populations Rules & laws succeeded basic customs. individuals have acquired rights and responsibilities

Relative importance of genetic and cultural evolution Human cultural evolution Occurring at a very fast rate Neolithic revolution to industrial revolution Silicon revolution/ information revolution of today.

Outline the difference between genetic and cultural evolution (2 Pt). genetic evolution occurs through variation and reproduction / inheritance of genes;
 cultural evolution occurs through customs / languages, etc. taught / learned; Mader: Biology 8th Ed.

Discuss how cultural evolution in humans depended on increases in brain size. (3 pts) large brain size correlates with language;
large brain correlates with improvements in tool-making; improved tools allow more nutritious diets for further brain development; increased brain size leads to rituals / burying the dead; excellent eye-hand coordination; increased brain size leads to written history / 
cave art / symbolic thought; Mader: Biology 8th Ed.