1) reduction in side of the chewing complex (smaller face, jaws and teeth)
- this is linked to Homo erectus' full commitment to material culture as an adaptive strategy.
2) increased brain size
- developed an increasingly innovative and complex technology, including more elaborate tools, organized social hunting and controlled use of fire.
- Oldowan tool use
3) Increased body size
- These developments of stone tools facilitated greater access to protein and improved nutrition generally. Improved nutrition explains the rapid increase in body size.
- Genus Homo is defined by relatively large brain, small face and jaws, and dependence on material culture for survival.
- Early Homo has a large brain, small jaws and dependence for material culture for survival. Early Homo experienced an enlargement of the brain and a general gracilization of the chewing complex.
- Earliest members of the genus Homo = Homo habilis (2.5-1.8mya) and Homo erectus (1.8mya - 300,000 yBP). Compared to australopithecines, early Homo habilis experienced an enlargement of the brain and a general gracilization (reduction of bone mass) of the chewing complex. These developments were linked with an increased focus on tool production and tool use, increased dietary diversity, and increased intelligence. Homo erectus continued reduction in size of chewing complex (smaller face, jaws, and teeth), increased brain size, increased body size, and first evidence of modern limb proportions. Early homo also had rapid increase in body size, likely because of greater access to protein / improved nutrition due to more elaborate tools, social hunting, and controlled use of fire.
- These developments were linked with an increased focus on tool production and tool use, increased dietary diversity and increased intelligence.
- Homo erectus had increased intelligence and full commitment to material culture as an adaptive strategy, setting the stage for emergence and evolution of Homo sapiens.
- Homo rudolfensis, its type specimen being KNM-ER 1470, was found in Lake Turkana, Kenya, along with a Homo habilis skull, KNM-ER 1813. Both skulls are from roughly 1.9mya. Originally, these two skulls were thought to be of the same species with their morphological differences being explained as the result of sexual dimorphism. The h. rudolfensis skull was thought to be a male skull as it is considerably larger, with a large face and larger brain size. The h. habilis skull was thought to be the female as its features are smaller: smaller face and smaller brain. The h. rudolfensis skull has large teeth and a more slight browridge. While the h. habilis skull has small teeth but a strongly pronounced browridge. These anatomical differences would support the notion that these two skulls are of the two different species, not one species with a great deal of sexual dimorphism.
- Sexual dimorphism, the differences in appearance between males and females of the same species, such as in colour, shape, size, and structure, that are caused by the inheritance of one or the other sexual pattern in the genetic material.
- The Homo Habilis found on the eastern side of Kenya's Lake Turkana is sometimes called Homo Rudolfensis. The major difference is that H.Rudolfensis is somewhat bigger than H. Habilis. They have the same general body plan and overall morphology (bigger brains and smaller faces). They are of the same species and have similar over body plan but differ in size - therefore making them in relation to sexual dimorphism. (Note: some researchers believe them to be separate species which would not make them relate to sexual dimorphism).
- It can be argued that because of the similarities in features of Homo Rudolfensis and Homo Habilis, they are part of one single, sexually dimorphic species. They both have robust jaws and both had very large brains. It can be argued that the Homo Rudolfensis fossils are the males because they are slightly larger, and the Homo habilis are the females because they are slightly smaller, exhibiting sexual dimorphism. But, evidence would suggest that they are two different species.
- The combined presence of archaic (Neandertal) and modern anatomical characteristics in some late Pleistocene European skeletons and the overlap in DNA structure indicate that Neanderthals were not replaced by modern H.Sapiens.
- Rather, instead of disappearing through extinction, Neanderthals were assimilated through admixture with early modern Homo Sapiens.
- Admixture revealed in the fossils-from physical characteristics in bones and teeth and from the DNA.
- Thus, the fundamental details of modern human anatomy probably have a single place of origin (Africa), but Neandertals later contributed to the European gene pool.
- The records show that their behaviors, both in form and in symbol, were similar to modern humans'.
- The size and robusticity of their large bones show that Neanderthals were highly physically active, more so than living humans. The empirical evidence disproves arguments that Neanderthals were less than human.
biological species concept
- Two organisms are species if they interbreed
- This is the most widely accepted definition of speciation
- Keeping in line with this argument, the fact that Neanderthal and modern anatomical created an admixture in modern H.Sapiens means that the interbred and produced fertile offspring.
- They are separate species, and in fact some evidence suggests they have not shared a common ancestor for at least 500,000 years. However, the two species lived alongside each other for centuries, successfully interbred with each other, and managed to transmit significant amounts of genetic material — DNA is more than 99% shared with humans. There are a few anatomical differences between the two species 1) a separate (though not better or worse) nasal structure in Neanderthals, 2) a thicker and more dense bone structure 3) smaller skulls and brain cases than AMHs 4) Neanderthals had differently formed oral cavities which limited their ability to produce speech. Also, culturally, they were quite different, despite their ability to interbreed — it is hypothesized that Neanderthals eventually became extinct just from competition from humans. Humans had more complex command of language, more energy-enriching diets, etc. New studies have pointed to gene activation as a distinguisher → even though humans and Neanderthals share a lot of the same genes, they are activated or not activated differently in the different species.
- Art and tools can tell us about how sophisticated the culture of its creator is, and how cognitively developed their creators are.
- For example, primitive stone tools of the Lower Paleolithic era tell us that the first hominis were sufficiently advanced in their brain development to manipulate their environment, which can also affect their diet and their ability to hunt.
- This culminates into the Oldowan Complex, the first hominid culture., which is assumed to be useful in cutting away the meat of animal tissues.
- Art can also tell us that its creator has a sufficiently complex symbolic communication system.
- For example, cave art indicates that Homoonins in those had communicated between families and future generations about storytelling and hunting behaviors, or communicated symbolically about burials of the dead.
- The usage of tools suggests that their creators had advanced cognitive ability to make these tools. For example, the Levallois technique used to produce Mousterian tools indicated that Neanderthals had the ability to visualize the shape and size of a tool from a stone core which was an advanced cognitive ability. In addition, tools indicated the Homo's capability of eating a greater range of food which enabled adaptive success for the species. In the Upper Paleolithic, the tools were complex, so to that of modern humans, that indicated precise, manual dexterity required for the crafting of such tools. The cave art of seals done by Neanderthals, the human-lion carved out of ivory found in the Upper Paleolithic, the wall murals, and the carved head of a woman from the Upper Paleolithic shows that the creators had the cognitive ability to create these detailed figures and had fine, precise dexterity to carve sculptures and draw the pictures. In order to carve these detailed and sculptures, fine and precise dexterity would have been required.
- During early Homo 's evolution, hominins began to colonize areas of the world outside Africa. The earliest record of H. erectus comes from Africa, less than 2 mya. At Ileret, on the eastern side of Lake Turkana, the partial skull of a very small H. erectus —possibly a female—was found in geologic strata dating to about 1.6 mya. Other key H. erectus fossils from Africa include a partial cranium found in Olduvai Gorge and dating to about 1.2 mya. The earliest evidence of H. erectus in Asia consists of ﬁve skulls, other bones, and many stone tools found in Dmanisi, Republic of Georgia. The date for this site, 1.8 mya, indicates that H. erectus colonized western Asia very soon after it began to evolve in Africa and H. erectus rapidly spread eastward from western Asia. The earliest fossil evidence of H. erectus in western Europe is from the Sierra de Atapuerca, northern Spain—at the cave sites of Sima del Elefante, dating to about 1.2 mya.
- Homo Erectus migrated out of Africa between 1.8 and 1.7 years ago. Homo Erectus migrated out of Africa might be because of an increase in cultural complexity or because of a breakdown of a barrier at the Suez bottleneck. They had the opportunity and it was possible for them to leave Africa. They migrated. Their initial settlement occurred in the tropical areas of Asia. The earliest sites are Ubeidiya (1.5-1.8 MYA), Dmanisi (1.5-1.8 MYA) and Perning (1.6-1.8 MYA).
- Humans reached Australia, specifically Lake Mungo in NSW, 40,000 YA. They could go to Australia because land surfaces that were previously were submerged by water were exposed and available for human occupation and movement between land masses. To traverse open water from South East Asia to Australia, late Pleistocene humans would have needed sophisticated boating technology and equally sophisticated navigation skills. No evidence of such technology and skills has been found. Modern humans seem to have had simply enough know-how to reach Australia.
- Migrations to America occurred via a land route. The land route was across the Bering land bridge, connecting Siberia and Alaska. The land route was created when sea levels reached a low point during the later Pleistocene, exposing areas of land that are now submerged. Migrations from Asia to North America took place sometime around 15,000 years ago.
1) Reasons for migration: population increase, disappearance of food resources, increased competition with neighbors for remaining resources, and climate deterioration. As population sizes began to outgrow carrying capacities, humans began to move from 3 inhabited continents to other regions.
2) Migration to Australia - late Pleistocene, around 50,000 yBP
- Around this time, sea levels much lower than they are today, allowed for people to occupy land masses that are now submerged. Australia, New Guinea, and Tasmania = single landmass (Greater Australia). Even so, much water separated Australia from Asia...no evidence of sophisticated boating technology or navigational skills among late Pleistocene humans....modern humans seem to have had simply enough know-how to reach Australia across open seas, which they ultimately colonized
3) Earliest archaeological evidence of humans in Australia is from Lake Mungo, dating to about 40,000 yBP with high skulls and rounded foreheads and small browridges, which differ from more modern skulls found in Greater Australia...Disparity between ancient and modern genes in Australia: likely explanation that the mtDNA sequence in ancient anatomically modern people has not survived to the present
4) Migration to Americas - 15,000 yBP
Similar front teeth shapes suggest single founding population from Asia to Americas via one migration, dental and genetic evidence points to Northeast Asia for native New World people's origin
- Adapted to cold, dry climates - founding humans were adapted to extreme environments at the margins of human capabilities
Migrations occurred via a land route across the Beringea (Bering land bridge) connecting Siberia and Alaska - land route created when sea levels reached a low point during later Pleistocene, exposing land that's now submerged
- One of the biggest distinguishing features of modern humans is our large brain. In early evolutionary stages (Aus. → early Homo) evolution tended to happen more with bipedalism and the ability to make tools, though brain size increased slightly along with these. For the first two-thirds of our evolution, early hominins had brain sizes relatively comparable to modern apes → volumes of around 400-500 mL. Homo habilis appeared around 1.9 mya and recorded a noticeable jump in brain size from predecessors. The first fossil skulls of Homo erectus, from about 1.8 mya, have brain sizes averaging about 600 mL. Around 600,000-200,000 years ago is when brain sizes began to expand rapidly → by about 500,000 years ago, brain sizes had reached 1000 mL. Now, modern humans have brain sizes of about 1,200 mL.
1)Australopithecus: 400-530 mL cc(cranial capacity)
2) Early Homo-510-800 mL, are in general larger and housed in a braincase with a higher, more rounded shape than the australopithecines.
3) Late Homo-large brain size 1,200 mL.
4) Homo Sapiens-1,300 mL
- Behavior cannot be fossilized however certain conclusions can be drawn from fossil evidence. One large indication of behavioral sophistication is burial of dead.Only 115,000 years ago was the deliberate burial of the dead introduced by Neandertals. Anatomy can give great insights into behavior. Based on pelvis size and shape as well as other characteristics such as the location of the foramen magnum can indicate whether the hominin walked bipedally. Tools found near campsites can demonstrate the intelligence of the hominins that camped there. Early tools such as flakes of rock indicate low levels of intelligence. Other tools, specifically hammers show high levels of intelligence. The presence of burn marks also indicate behavioral sophistication and intelligence. Homo Erectus was the first hominin to harness fire. The final indication of behavior comes from grouping of fossils indicating family units. The Laetoli footprints found by Mary Leakey in Olduvai gorge indicate two hominids walking together. It is even assumed the female is carrying a child due to the inconsistent angle of her foot. Fossils like these indicate these humans travelled in family groups.
- One of the primary indicators of human behavior is tools. Tools, such as hand axes or spears, can be dated to specific time periods of human evolution. For example, the Schöningen Spears
are light wooden throwing spears from the paleolithic age found in a German mine. They are the oldest (more than 400kya) completely preserved hunting weapons in the world and they are regarded as the first evidence of the active hunt by H. heidelbergensis. Light throwing spears tell us that H. heidelbergensis was able to hunt without getting to close to their prey, preventing injury. Additionally, the locations of fossils can give us information about whether the dead were intentionally buried. Intentional burial is one of the earliest pieces of evidence we have for early hominin culture and deliberate, ceremonial action. Evidence of deliberate burials found at Qazfeh in Israel, Atapuerca in Spain, La Chapelle, etc. Finally, decorations and paintings indicate the capability of storing information outside of the human brain. For many years, cave paintings dating back 30,000 years in southern France were believed to be the earliest example of the use of symbolism by a hominid species. However, in the last few years, archeologists have discovered other possible examples of Neanderthals using symbolism.
- Biological basis of human variation explains that there's great genetic diversity within all human populations, so pure races (genetically homogenous populations) don't exist in the human species today or ever in the past!!! (back off 2 racists ~_~)
- Some differences between populations in different geographic areas of the world are strongly inherited, but others (body size and shape) are strongly influenced by nutrition, way of life, and other environmental features
- Biological consequences of mating depend only on individual genetic makeup of the couple, not on racial classifications. No biological justification for restricting intermarriage.
- ~Race is a social construct~
Fran Boas showed plasticity of human types
Morton Collection controversy - collecting human skulls to try and show cranial capacity of certain races means they're biologically inferior (Morton measurements correct but conclusions erroneous, cranial capacity variation in human populations appears to be largely a function of climate, and not bearing on intelligence)
Humans demonstrate clinal variation
Lewontin and genetic variation studies show there is more variation within populations than between them.
- Adaptation to environment is the center of human variation. Multiple skin color hypotheses: Vitamin D produced in skin, protects from rickets, sunlight needed for vitamin D metabolism, light skin allows greater UV penetration in less time (good in temperate zones where less US rays and sunshine hours), dark skin requires more exposure for required vitamin D amount, adaptation for environment (equatorial populations w/ dark skin are protected against powerful UV rays)
- Ancestry =/= race, some traits found in higher frequencies in some groups - used to estimate ancestry
- All humans today are part of the same species, homo sapiens sapiens. There is some debate as to the origin of each specific race. The multiregional evolution model states that humans at different locations evolved convergently. The single origins model or "Out of Africa" states that humans all come from the same ancestor which migrated out of Africa to all parts of the world. Regardless of origins, all humans today are members of the same species. Human biological features are subject to change over time.The human features which have universal biological value for the survival of the species are not known to occur more frequently in one population than in any other. Each race has specific cultural characteristics. However there is no causal linkage between these physical and behavioral traits, and therefore it is not justifiable to attribute cultural characteristics to genetic inheritance. The genetic capacity for intellectual development is one of the biological traits of our species essential for its survival. This genetic capacity is known to differ among individuals. The peoples of the world today appear to possess equal biological potential for assimilating any human culture.
- also, there are gradients, there are no pure races and race is just a social construction. if you understand the biology behind why humans in northern latitudes have lighter skin, this refutes race in itself.
Simply put, humanness can be defined as being aware. Linnaeus embodied this concept in 1758 by naming humans Homo Sapiens meaning "Thinking man". Aristotle believed that humanness is the ability to reason. Neither of these qualities are specific to modern humans or humans at all. Through use of tools, even crude tools like flakes, early hominids indicated their awareness of their surroundings and their ability to reason. Homo Erectus's use of fire indicates strong reasoning abilities. Humanness can go back to australopithecines who travelled in groups. Staying in groups demonstrates awareness as well as reasoning skills. One does not have to possess modern human features to produce "human" behaviors. Dogs demonstrate awareness by their ability to understand human commands. One famous story of animal reasoning involves a 2009 bus fire in Australia during which a kangaroo stayed in close proximity to two humans in a culvert in order to survive. Humanness developed early on in evolution and human traits are not specific to humans.
- art-creating a version of yourself, believing it
- why do we care-ritualizing death, burial of the dead
- unique for-organized religion
- being aware/rationalizing
- 'humanness' as those abilities human ancestors developed such as speech, art, and culture. As discussed in the PBS Becoming Human documentary, the ability to store information outside the human brain, in this case through art, was a major development in human evolution. Being able to pass on information to future generations defines humanness. Specifically, about 140kya when AMH were pushed to the brink of extinction and only about 600 breeding individuals remained, at Pinnacle Point, South Africa, for example, AMH used red ochre to paint designs on walls indicating an understanding and use of symbolism.
- So much of our understanding of early hominins and human evolution is based on inference and sophisticated guesswork. But there are some things we can say with some sureness based on the fossil record. First, and perhaps most broadly, since the appearance of early Homo species, we can say with almost certainty that the Homo family was at one point much larger — we have evidence of several different early human species living at the same time, often in the same place, like at Lake Turkana. And yet, we are the only species that survived. The presence of these hominin fossils can certainly tell us about how humans evolved. For example, we know that bipedalism was a feature of hominins before the Homo species even appeared. We also can gain evidence from other things uncovered by the fossil record. For example, the presence of tools, paintings, and ceremonial burials can tell us about how early human societies might have functioned and the cultural practices they might have adopted. But, despite the fact that all of these are based in the fossil record, there is still some guesswork involved in it, which has led to many debates. In addition, the presence of some forged or unreliable fossils like the Piltdown man have created some controversy.
- There are several species in the genus homo. Included are Homo Habilis, Homo Rudolfensis, Homo Naledi, and Homo Erectus. Homo Erectus is the first to be considered a human ancestor. After the appearance of homo there is some debate and controversy as to the appearance of Homo Sapiens. The multiregional evolution model states that humans at different locations evolved convergently. In Europe there were neanderthals which evolved into Homo Sapiens. In Asia, Homo Erectus evolved into Homo Sapiens. The same occurred in Africa and Australia, all completely independent. The single origins model or "Out of Africa" states that humans evolved in Africa and migrated out of Africa to all parts of the world. Some argue lack of realism in this model because it seems improbable that this one species could beat out archaic species all over the globe. Some suggest this species carried diseases which wiped out all archaic species. The most accepted theory now involves a combination of the two. In which Homo Sapiens migrated out of Africa and interbred with different Archaic species.
- 200,000 - 6,000 yBP
- Earliest evidence of modern people's anatomical characteristics, come from Ethiopia's Middle Awash River Valley and southern Ethiopia
Cranial capacity of about 1,450 cc, close to average for modern humans
- Many other characteristics are essentially modern - relatively tall cranium, vertical forehead, smaller browridges, and a nonprojecting face. Among archaic features are significant browridges (even though trending towards smaller) and a relatively long face. These remains may be from earliest modern people in Africa or at least close to the earliest.
- Remains indicate that modern people emerged in Africa long before arrival in Europe and western Asia
- Klasies River Mouth Cave - documented the presence of a chin (distinctively modern characteristic), Hofmeyr - nearly complete skull, striking resemblance to modern Europeans
- Skulls still bear some robusticity - flaring cheekbones, well-developed browridges - different from gracile features of modern humans
- One of several individuals found in the Kabwe (Broken Hill) lead mine in Zambia has enormous brow ridges, but the facial bones and the muscle attachment areas on the back of the skull for the neck muscles are quite small compared to with those of H.Erectus in Africa. The skull is similar to those of early archaic hominins from Europe. Both Zambian (African) and European skulls have erectus like characteristics: a large face, large brow ridges and thick cranial bones.
- One of the biggest failures in the field of human evolution and evolutionary genetics is the lack of communication between the different fields and different scientists. Building the story of human evolution requires not just one field of research, but many coming together — archaeologists must come together with cultural anthropologists and chemists and physicists. However, many of these fields tend to be closed off from each other. For example, when the Piltdown Man was originally discovered, the fossil was identified as significant using only anatomical studies and comparisons to other existing fossils. It was not until later that the fossil underwent more significant scientific testing that revealed the tiny file marks on the teeth and the fact that the teeth and the skull had come from fossils of two different ages. However, when all these different fields of science do come together, they can produce some pretty amazing results, like the Neanderthal genome project. That project, which successfully managed to code the entire DNA structure of Neanderthals from existing fossils, was one of the greatest successes in recent evolutionary science. However, that could not have been possible without archaeologists excavating those remains, geologists dating them, chemists and physicists coding the actual DNA, and anthropologists taking that information and contextualizing it and making it significant.
- One problem that occurs often in evolutionary studies is dating accuracies. Carbon-14 dating is the most commonly used form of dating in laboratories. Like every lab process this dating has flaws. A complete fossil record would greatly advance the field. Identification of fossils is also morphological and subjective.