Evolution (chp.1) Flashcards
Orrorin Tugenensis ( O. Tugenesis)
Was the earliest hominin hypothesized to break off from the great apes was found in Tugen Hills, Kenya in 2,000 C.E
-their teeth indicate they were closer to modern humans than to Australopithecines
-in their arms and hands, though, showed characteristics needed for tree climbing , so still tied to an environment in the tress
Lucy (Australopithecus Afarensis)
Lucy was found in 1974 in the Awash River Basin of Afar, Ethiopia. At the time she represented the oldest Hominin and fossil to be discovered. As an example of a Hominin group known as Australopithecus Afarensis, Lucy showed some signs of being able to walk upright., but likely prefer to walk on all fours like the modern baboon. Scientists have dated the remains of Australopithecus Afarensis as living between 3.4 and 2.9 million years ago.
Australopithecines
6 million years ago the first hominins diverged from the great apes ( Gorillaz chimpanzees and orangutans). And began a slow evolution crawl towards modern humans it is generally accepted that humans emerged from the branch of hominins known as Australopithecines
Taung Child (Australopithecus Africanus)
The Taung child was discovered in 1924 outside Johannesburg, South Africa. This fossil Hominin lived from 2.8 to 3.3 million years ago, look like a cross between the great apes and modern humans and was labeled Australopithecus Africanus. This group emerged in Africa, roughly 3.6 million years ago and it’s thought to have died around 2.1 million years ago. This species of hominins it’s widely recorded as being an evolutionary closer to humans than to apes and is this considered the branch of hominins from which humanity would emerge.
-discovered by Raymond Dart
Why did the hominins in Africa stand up?
-natural selection: global climate and environmental changes, drove the animals to rapidly adapt their behaviors to survive those species that could not adopt died out.
- Desertification: this process meant that forest lands, which once covered the bath Saharan desert and its fringes were rapidly disappearing.
Opposable Thumbs
The increasing dexterity and use of these species hands eventually led to the unique process of tool-building and tool-use to survive .Allowed hominins to grip, grasp, manipulate and carry out fine motor skills.
Homo Habilis “the skillful man”( Dear boy)
The first true human or member of the class homo was Homo Habilis. This group of protohuman dated between 2.3 to 1.6 million years ago they would walk up right at all times like their predecessors. However, unlike many of the hominins that came before them, Homo habilis represent a large jump forward in terms of brain, structure, and brain size. These developments in the brain structure and size led to the species, mastering the art of creating stone tools. The brain size of Habilis was twice of any previous known hominins.
Dear boy ( Homo Habilis)
The remnants of this species was four in Olduvai Gorge, Tanzania by Mary and Louis Leakey in the 1950s. The Leakeys unearthed the fossils remains of Dear boy, a 1.8 million year old habilis. Whose burial place was surrounded by stone tools for butchering and hunting large game animals.
Homo Erectus “ The Upright Man/human”
-They live between 1.8 million and 200,000 years ago. this species was more fully by petal than their earlier ancestors they harnessed the power of fire a new development for the hominins.
-The vocal cords were developed enough to speak, suggesting that some form of language develop among this group .
-In terms of phenotype, they began to resemble modern humans as a loss much of their body hairs .
-the braincase of homo erectus grew much larger than previous hominins
- Homo erectus children with developmentally and physically far more slowly than other creatures in the Animal Kingdom. The child’s brain would develop over a longer period of time, forcing homo erectus to develop more time to childcare and rearing
-this long gestational and growth period, as well as the transmission of knowledge from one generation to the next (education) became a hallmark of humanity and began with homo erectus
-discoveries in Asia and Europe
Homo sapiens: Anatomically Modern Humans
-Homo sapiens are anatomically. Modern humans were highly social creatures that developed during another episode of climate upheaval. Our species developed complex and representative language that allowed for greater communication and cohesion in the species.
-Humans have only been around for at best best 200,000
-modern humans bird survived the pressure of climate and environmental change that would drive other hominins to extinction. Evidence suggest that Homo sapiens numbers dwindled to just a few thousand that remained in African forest conditions elsewhere became more favorable.
- every human on the planet can be traced back to a small population of a few thousand people that survive in Africa
Homo Heidelbergensis
-700,000 to 200,000 years ago they developed in eastern and Southern Africa before spreading to North Africa and Europe.
-They populated Europe before the rise of Neanderthals and Denisovans
- some have theorized that they were a contemporary of homo erectus and probably an offshoot group that moved directly north, while homo erectus moved north and east, out of Africa
Neanderthals
Left Africa roughly 150,000 years ago and settled in modern day Europe. Shorter, stockier and stronger than their Homo sapiens cousins, they lacked the dexterity and cognitive ability to think symbolically and abstract that modern humans possessed
- DNA compromises between 1% to 4% of the human gene pool at present, with higher concentrations found in people of European descent
- This group was unable to compete with the new Homo sapiens arrivals in Europe- leading to their demise
Denisovans
-Left Africa before the Neanderthals. They may have been a relict population of stone-tool users that ,ingrates to Asia and populated that region as early as 3 million years ago, in the lower Paleolithic period.
-Like the Neanderthals this group would slowly succumb to the pressure from their migrating cousins, the Homo sapiens
- dna compromises between 3% to 5% of indigenous populations found in Oceania, Melanesia, and papuans
Time line
Orrorin tugenesis- 6 million years ago
Australopithecus anamensis -4.2 million years ago
Australopithecus afarensis (LUCY)- 3.4 million years ago
Australopithecus africanus- 3.0 million years ago
Homo Habilis (dear boy)- 2.5 years ago
Homo erectus and homo ergaster (java and Peking man)- 2 million years ago
Homo heidelbergensis (Neanderthals and homo sapiens)- 600k years ago
Homo neandethalis- 200k years ago
Homo sapiens 200k years ago
Homo sapiens (modern humans ) - 35k years ago
Hominids
The family, in scientific classification, that includes gorillas, chimpanzees, and humans(that is, Homo sapiens, in addition to our now-extinct hominin ancestors such as the various Australopithecines as well as homo habilis, homo erectus, and homo neanderthalensis )
Hominins
A scientific classification of modern humans and out now-extinct ancestors, including Australopithecines and others on the genus homo, such as homo habilis and homo erectus.
Hominid has been expanded to include the great apes, gorillas, chimpanzees, and orangutans
What distinguished humans from other hominids?
1.lifting the torso and walking on two legs(bipedalism), thereby freeing hands and arms to carry objects and hurl weapons
2.controlling and then making fire
3. Fashioning and using tools
4. Developing cognitive skills and an enlarged brain and therefore the captaincy of language
5. Acquiring a consciousness of “self”
All these traits were in place at least 150,000 years ago
Evolution
Process in which species of plant and animals change over time, as a result of the favoring, through reproduction, of certain traits that are useful in that species environment.
-Implies successful adaptation to environmental surroundings
Australopithecines
Hominin species, including anamensis, Afarensis (Lucy) and africanus, that appeared in Africa beginning around 4 million years ago and unlike other animals, sometimes walked on 2 legs. Their brain capacity was little less than one-third of a modern human. Although not humans, they carried the genetic and biological material out of which modern humans would later emerge/
Sahelanthropus tchadensis
“Toumai skull”
-7 million years ago
-small cranial capacity like a chimp’s but more human-like teeth and spinal colum placement at the base of the skull.
-they walked up right
-their (Orrorin and sahelanthropus)teeth indicate they were closer to modern humans than Australopithecines
Homo Naledi
Far inside a cave near Johannesburg, South Africa.
Upper body parts resembled pre-homo finds, while the hands, wrist, and legs are close to those of modern humans
335,000 to 236-000 years agp
Homo habilis
Species confined in Africa, that emerged about2.5 million years ago and whose tool making ability truly made it the forerunner, though a very distant one, of modern humans. Homo Habilis means “skillful human”
Homo erectus
Species that emerged about 1.8 million years ago, had a large brain,walked truly upright,migrated out of Africa, and likely mastered fire.
Homo erectus means “standing human”
“Java man ”
Found in 1891 on the island of Java, turned out to be those of an early homo erectus that had dispersed into Asia nearly 2million years ago.
