Human evolution

by Irene74
Last updated 5 years ago

Discipline:
Science
Subject:
Biology
Grade:
9,10,11,12

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Human evolution

EVOLUTION FROM AUSTRALOPITHECUS TO HOMO SAPIENS

Austrolopithecus anamensi -Combination of both traits apes and humans. -Size similar to that of modern chimpanzees, -Strong male-female size difference (sexual dimorphism) - Small brain. -Thickly-built, long, narrow jaws with side rows of teeth arranged in parallel lines. -Generally they are plant-eaters. -The upper end of the tibia (shin bone) shows an expanded area of bone and a human-like orientation of the ankle joint, indicative of regular bipedal walking (support of body weight on one leg at the time). -Long forearms and features of the wrist bones, suggest they probably climbed trees.

Derived from the Latin word ‘australo’ meaning ‘southern’ and the Greek word ‘pithecus’ meaning ‘ape’.

Austrolopithecus garhi-Similar in appearance to A.afarenis but has more advanced features in the teeth.-Brain size slightly larger than A.afarensis.-Very large canines, molars and premolars and thick tooth enamel, rectangular or U-shaped dental arcade, diastema is present in the upper jaw. -Projecting lower face and sagittal crest, for anchoring large jaw muscles.-Limb bones

Austrolopithecus afarensis also known as Lucy’s species-Ape and human characteristics:-Ape-like face proportions (a flat nose, a strongly projecting lower jaw, a low sloping forehead) -A small brain-Long, strong arms with curved fingers adapted for climbing trees. -Small canine teeth.-A body that stood on two legs and regularly walked upright. Males were larger than females.-Their adaptations for living both in the trees and on the ground helped them survive.-Marked sexual dimorphism:is: systematic difference between individuals of different sex in the same specie

Australopithecus africanus-Brain size similar to apes -Some prostorbital constriction.Small canine teeth, no diastema (gap between the canines and adjacent teeth). Fairly parallel tooth rows.-Relatively long arms. Curved finger bones, thumb/finger lenght similar to humans.-Lumbar curve of spine. Illiac blade short, wide and twisted towards the side. -The skull showed some slightly more human-like features such as a smaller brow ridge and a slightly arched forehead area.-Shaft of femur angles in, placing knee over foot.-Hip and leg bones show that they were small-bodied but regularly walked upright.

Paranthropus aethiopicus-The bony ridge (sagittal crest) on the midline of the top of the skull indicates huge chewing muscles, with a strong emphasis on the muscles that connect toward the back of the crest and created strong chewing forces on the front teeth. -It is likely to be the ancestor of Paranthropus boisei.

Paranthropus boisei-Characterized by a specialized skull with adaptations for heavy chewing. Members of this species had a bony ridge (sagittal crest) on the midline of the top of the skull. This crest anchored the large chewing muscles from the top and side of the braincase to the lower jaw, and this moved the massive jaw up and down. The force was focused on the large molars and premolars. -Cranial capacity in this species suggests a slight rise in brain size (about 100 cm in 1 million years)

Paranthropus robustus-Had a bony ridge (sagittal crest) on the midline of the top of its skull and a massive face, both adaptations for chewing tought food. Althought often called `robust australopithecine´, it is now known that `robust ´ refers solely to its tooth and face size, not to its body size.

Paranthropus were bipedal hominids that probably descended from Australopithecus.

Homo rudolfensis-Originally considered to be Homo Habilis, the ways in which H. Rudolfensis differs is its larger braincase, longer face, and larger molar and premolar teeth. Due to the last two features some scientists think this species might be considered an Australopithecus, although one with a large brain!

Homo habilis -Its name, which means ` handy man´ , was given because this specie represent the first stone toolmaker.-Has a slightly larger braincase and smaller face, jaw and teeth than in Australopithecus They were arranged in a rounded arc like those of modern humans.- Retains some ape-like features, including long arms and a moderately-prognathic face.-Features of the leg and foot bones indicate that this species walked on two legs.

Homo erectus -They were the first early humans to make hearths, to eat significant amount of animal meat and bone marrow, and to care for the old and weak. They were the longest-lived species on our family tree.-The oldest known early humans to have possessed modern human-like body proportions with relatively elongated legs and shorter arms compared to the size of the torso. These features are considered adaptations to a life lived on the ground, indicating the loss of earlier tree-climbing adaptations, with the ability to walk and possibly run long distances. --Small generalized teeth and thick tooth enamel. Robust jaw. Fully bipedal anatomy,-Noticed an expanded braincase relative to the size of the face.

Homo heidelbergensis -Very large brain size . Some have thick cranial bones. Lightly built skull. Higher skull than Homo Erectus. Large face. Midsize brow ridges. Small, generalized teeth. Lower premolar has two cusps. Thick tooth enamel.Robust jaw. Modern body prportions and hand.Fully bipedal anatomy.-Present slight sexual dimorphism, as in people today.

Homo neanderthalensis-Are our closest extinct human relative. Some defining features of their skulls include the large middle part of the face, angled cheek bones, and a huge nose for humidifying and warming cold, dry air. -Their bodies were shorter and stockier than ours, another adaptation to living in cold environments. But their brains were just as large as ours and often larger - proportional to their brawnier bodies. They have fully bipedal anatomy.-The first early human to have language, bury their dead, and exhibit symbolic behaviour.And the first to wear clothing.

Homo sapiens-Very large brain size (1000-1700 cm3 ) Thin cranial bones. Lightly built skull. Rounded skull vault. Slightly projecting face.No pronounced brow ridges. Small, generalized teeth. Lower premolar has two cusps. Thick tooth enamel. Lightly built jaw. Modern body proportions. Modern hand.Fully bipedal anatomy.-Slight sexual dimorphism, like in people today.

Homo floresiensis also known as `hobbit´-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, they made and used stone tools, hunted predators and may have used fire. -The diminutive stature and small brain is a result 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.

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