Evolution-Human Evolution

Biology: FezzaMiami Arts Charter

Biogeography- the study of the distribution of species and ecosystems in geographic

space and through (geological) time- Evolution is modification over time-

Molecular Biology- Molecular biology is a branch of science concerning biological activity at

the molecular level. The field of molecular biology overlaps with biology and chemistry and in particular, genetics and biochemistry.

- Molecular biology study genes in RNA and DNA as well as the molecules that regulate these reactions and compare them against other species.

- All life has similar structures/molecules that can perform life’s basic functions

- https://m.youtube.com/watch?v=nvJFI3ChOUU

Observed Evolutionary Change- most speciation takes millions of years- take a mass of mutations accumulating over generations to create a

different species- But all it takes is some event that reproductively isolates one group of

individuals from another to cause genetic drift in a population

- evolution is easiest to observe in species with a quick generation turnover- https://www.youtube.com/watch?v=ikZQPB45Zbw

Human Evolution: Our Early Ancestors- Humans are primates- Modern Human Species: Homo sapiens- Share a common ancestor with modern day African apes, gorillas,

chimpanzees, and bonobo etc., 8-6 mya- The fossils of early humans who lived between 6 and 2 million years ago

come entirely from Africa.- 15-20 species of early humans

Human Traits- Bipedalism, the ability to walk on two legs, evolved over 4 million years ago. - Large and complex brain, the ability to make and use tools, and the capacity

for language, developed more recently. - Many advanced traits, including complex symbolic expression, art, and

elaborate cultural diversity, emerged mainly during the past 100,000 years.-

Humans Family Treehttp://humanorigins.si.edu/evidence/human-family-tree

Sahelanthropus Tchadensis- Sahelanthropus tchadensis is one of the oldest known species of humans- Between 7 and 6 million years ago in West-Central Africa- First appearance of Bipedalism - Evidence: The foramen magnum (the large opening where the spinal

cord exits out of the cranium from the brain) is located further forward (on the underside of the cranium) than in apes or any other primate except humans

- Indicates that the head of Sahelanthropus was held on an upright body, probably associated with walking on two legs.

Foramen Magnum

Orrorin tugenensis- Femur bones shows evidence of bipedalism- Probably climbed trees and walked upright- Between 6.2 and 5.8 mya

Ardipithecus ramidus- Ardipithecus ramidus a partial skeleton (like most)- The foot bones in this skeleton indicate a divergent large toe combined

with a rigid foot - Reconstructed pelvis show adaptations that combine tree-climbing and

bipedal activity- canine teeth like chimpanzee - found alongside faunal remains indicating she lived in a wooded

environment- contradicts the open savanna theory for the origin of bipedalism

- states that humans learned to walk upright as climates became drier and environments became more open and grassy.

Australopithecus afarensis AKA Lucy- remains from more than 300 individuals- Between 3.85 and 2.95 million years ago in Eastern Africa (Ethiopia,

Kenya, Tanzania)- survived for more than 900,000 years, which is over four times as long as

our own species has been around- oldest documented bipedal footprint trails

Au. afarensis Continued- children grew rapidly after birth and reached adulthood earlier than

modern humans- Shorter period of growing up

- less time for parental guidance and socialization during childhood.

- both ape and human characteristics: - Ape like face proportions (a flat nose, a strongly projecting lower jaw) and braincase (with

a small brain, usually less than 500 cubic centimeters, about 1/3 the size of a modern human brain)

- long, strong arms with curved fingers adapted for climbing trees- small canine teeth, and bipedal.

- Their adaptations for living both in the trees and on the ground helped them survive for almost a million years as climate and environments changed.

Australopithecus africanus- Au. africanus had a rounder cranium housing a larger brain and smaller

teeth- some ape-like features

- shoulder and hand bones indicate they were also adapted for climbing

- relatively long arms and a strongly sloping face that juts out from underneath the braincase with a pronounced jaw.

- Pelvis, femur bone, and foot bones of Au. africanus bipedalism

- Discover 1924: The Taung child, found in 1924, was the first to establish that early fossil humans occurred in Africa.

Paranthropus- very few remains of this species have been found- 2.5 million year old ’Black Skull’ in 1985 helped define this species as the

earliest known robust australopithecine. P. aethiopicus- has a strongly protruding face, large megadont teeth, a powerful jaw,

and a well-developed sagittal crest on top of skull, indicating huge chewing muscles

- Paranthropus robustus found in South Africa- Paranthropus boisei- larger brain capacity

Homo Rudolfensis- only one really good fossil of this Homo rudolfensis- KNM-ER 1470, from Koobi Fora in the Lake Turkana basin, Kenya- Originally considered to be Habilis- really critical feature: a braincase size of 775 cubic centimeters, which

is considerably above the upper end of H. habilis braincase size. At least one other braincase from the same region

- also shows such a large cranial capacity.

- differs is in its larger braincase, longer face, and larger molar and premolar teeth.

- Due to the last two features, though, some scientists still wonder whether this species might better be considered an Australopithecus, although one with a large brain!

Homo Habilis- one of the earliest members of the genus Homo- slightly larger braincase and smaller face and teeth than in

Australopithecus or older hominin species- retains some ape-like features, including long arms and a

moderately-prognathic face.- name means ‘handy man’, was given in 1964 because this species was

thought to represent the first maker of stone tools. Currently, the oldest stone tools are dated slightly older than the oldest evidence of the genus Homo.

Homo habilis continued- Discovery: 1960- A team led by scientists Louis and Mary Leakey at Olduvai Gorge in

Tanzania- The type speciman, OH 7, was found by Jonathan Leakey, so was

nicknamed "Jonny's child"- combination of features different from those seen in Australopithecus- declared these fossils a new species, and called them Homo habilis

- suspected that it was this slightly larger-brained early human that made the thousands of stone tools also found at Olduvai Gorge.

Homo erectus- Early African Homo erectus fossils (sometimes called Homo ergaster) are

the oldest known early humans to have possessed modern human-like body proportions

- relatively elongated legs and shorter arms compared to the size of the torso.

- adaptations to a life lived on the ground- indicating the loss of earlier tree-climbing adaptations

- ability to walk and possibly run long distances- expanded braincase relative to the size of the face

Homo erectus- complete fossil individual of this species is known as the ‘Turkana Boy’

- a well-preserved skeleton (though minus almost all the hand and foot bones)- dated around 1.6 million years old.

- Microscopic study of the teeth indicates that he grew up at a growth rate similar to that of a great ape

- Fossil evidence that this species cared for old and weak individuals. - The appearance of Homo erectus in the fossil record is often associated

with the earliest handaxes, the first major innovation in stone tool technology.

- Found in Asia- the first species to have expanded beyond Africa- highly variable species, spread over two continents- possibly the longest lived early human species - about nine times as long as our

own species, Homo sapiens, has been around

Homo Heidelbergensis- large browridge- larger braincase- flatter face than older early human species. - First species to live in colder climates- short, wide bodies were likely an adaptation to conserving heat- lived at the time of the oldest definite control of fire and use of

wooden spears- first early human species to routinely hunt large animals- the first species to build shelters, creating simple dwellings out of

wood and rock.

Discovery- Year of Discovery: 1908- Heidelberg, Germany, a workman found the type specimen of H.

heidelbergensis in the Rösch sandpit just north of the village of Mauer.- This mandible was nearly complete except for the missing premolars and

first two left molars; it is heavily built and lacks a chin. German scientist Otto Schoentensack was the first to describe the specimen and proposed the species name Homo heidelbergensis.

Homo Neanderthalensis- Neanderthals (the ‘th’ pronounced as ‘t’) are our closest extinct human

relative. - large middle part of the face, angled cheek bones, and a huge nose for

humidifying and warming cold, dry air. - shorter and stockier body, another adaptation to living in cold

environments.- Brains were just as large as ours and often larger - proportional to

their brawnier bodies.

Neanderthals- Neanderthals made and used a diverse set of sophisticated tools- controlled fire- lived in shelters- made and wore clothing- were skilled hunters of large animals and also ate plant foods- occasionally made symbolic or ornamental objects - Neanderthals deliberately buried their dead and occasionally even

marked their graves with offerings, such as flowers.- DNA has been recovered from more than a dozen Neanderthal

fossils, all from Europe; the Neanderthal Genome Project is one of the exciting new areas of human origins research.

Homo floresiensis AKA the Hobbit Remains of one of the most recently discovered early human species, Homo floresiensis (nicknamed ‘Hobbit’), have so far only been found on the Island of Flores, Indonesia. The fossils of H. floresiensis date to between about 100,000 and 60,000 years ago, and stone tools made by this species date to between about 190,000 and 50,000 years old. H. floresiensis individuals stood approximately 3 feet 6 inches tall, had tiny brains, large teeth for their small size, shrugged-forward shoulders, no chins, receding foreheads, and relatively large feet due to their short legs. Despite their small body and brain size, H. floresiensis made and used stone tools, hunted small elephants and large rodents, coped with predators such as giant Komodo dragons, and may have used fire.

The diminutive stature and small brain of H. floresiensis may have resulted from island dwarfism—an evolutionary process that results from long-term isolation on a small island with limited food resources and a lack of predators. Pygmy elephants on Flores, now extinct, showed the same adaptation. The smallest known species of Homo and Stegodon elephant are both found on the island of Flores, Indonesia. However, some scientists are now considering the possibility that the ancestors of H. floresiensis may have been small when they first reached Flores.