Archaic humans and out of africa Flashcards
(43 cards)
By which three fields are we mainly studying human evolution?
We study human evolution through archaeology, anthropology and osteology (and also genetics nowadays)
Ethics is an important aspect of studies on human evolution, what are the main questions?
- Can we derive behaviors from morphology?
- Can we draw conclusions about behavior and capabilities based on material culture expressions?
if not, what else? or should we even try?
Does morphology and genetics match in human evolution studies?
No! Morphology and genetics reflect different ”aspects”. Longer back in time we only have morphology to go on. So they both have their place in the story.
What is really important to remember when studying human evolution?
We of course look at what we have, but its important to remember that just because we cant see it, it was never there. For example, stone preserves well, but wood does not. We are surely missing stuff in earlier periods, but we will never know the full picture.
How old are the oldest stone tools ever found?
The oldest tools are ~3.3 MYA. Very basic chopping tool.
The lithic stone tools are often described as different “modes”, how are they related?
The different “modes” of stone tools follows a sequence/chain/pattern where the younger ones seem to build on the previous mode or toolmaking technology.
The main question is, what can we say about the toolmakers, are these modes reflecting intellectual increase or just need? for example, what is “required” to make a mode 3 tool?
When did the different modes of stone tools appear?
Chronology (rough):
Mode 1 - 3.3 MYA
Mode 2 - 1.7 MYA
Mode 3 - 300 kya
Mode 4/5 - 80 kya
Describe mode 1 tools.
Mode 1 tools are characterized by unifacial (from the same side) flaking from direct knapping. The flakes all have cortex (outside) of the core showing. Flakes had hard edges and was probably of use, so both cores and flakes useful. The cores are not exhausted – possible to continue (or would have been possible).
These characteristics points to that these tools were produced for immediate use (found near carcasses with cut marks etc.) , but there seem to have been some transport of raw material, so sometimes planned. Some evidence of “handedness” L/R already here.
Which hominid species is associated with mode 1 tools?
Homo habilis, which translates to the handyman or the toolmaker got their name from being found with thousands of mode 1 tools and animal remains with signs of precision cuts and marrow extraction. Homo habilis also represents the earliest appearance of the genus Homo. However, there were other hominid species during the same time and in the same geographical area, so it is possible that other hominids also used tools. Also, the oldest mode 1 tools date back to 3.3 MYA which is before the estimated appearance of H. Habilis (~2.5 MYA), who made these ones?
The first mode 2 tools appear ~1.7 MYA, a very long time after the mode 1 tools started to be used. Describe the characteristics of mode 2 tools.
Mode 2 tools are characterized by bifacial flaking, aka hand axes - which required reshaping of the core. There was a clear sequence that needed to be done in order to produce these tools and there was a clear end picture (evidence of planning?). Also flakes useful, but seemingly the reshaped core was the end product.
The consensus is that another type of thinking is required to make this tool type, and the skill need to be transferred to others. But there was low level of standardization at this point.
Which hominid species is associated with mode 2 tools?
The appearance of Homo erectus in the fossil record (~1.89 MYA - 110 000 ya) is often associated with the earliest handaxes, the first major innovation in stone tool technology. But a lot of other hominids were also around during this time. Homo heidelbergensis is associated with more advanced Mode 2+ tools ~500 kya.
When is the earliest evidence of bipedalism from?
Sahelanthropus tchadensis is one of the oldest known species in the human family tree (6-7 MYA). Some of the oldest evidence of a humanlike species moving about in an upright position comes from Sahelanthropus. 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. This feature indicates that the head of Sahelanthropus was held on an upright body, probably associated with walking on two legs.
Ardipithecus (4.5-5 MYA) was a facultative bi-ped (capable of walking upright), probably similar in body and brain size to a modern chimpanzee. This seem to be the “beginning” of bipedalism, the climate changed a lot after 4 MYA - Trend: Colder- rainforests disappear - landscape more open - savannah?
Australopithecines were around at the time of the first stone tools 3.3 MYA, what do we know about them?
The Australopithecines gracile include four species A. anamensis - 4.3-3.8 MYA , A. afarensis- 4.0-3.0 MYA, A. africanus - 3.0-2.3 MYA and A. garhi - c.2.5 MYA and robus (also included in australopithecus: Paranthropus aetiopicus (c.2.5 MYA), Paranthropus boisei, Paranthropus robustus (South Afr.).
Clear bi-pedals, e.g. Lucy (A. Afarensis - survived for about 900 000 years!) with femurs that show indications of heavier load than chimps) but had ape like upper extremities (angled ridge of scapula where humans have horizontal and curved fingerbones. ), so they might still slept/lived in trees. The grasping foot is still present during this time ~3.5 MYA. A mix of ape-like and human like features that allowed then to take advantage of both habitats, ground and trees - likely to have been helpful when climate changed.
homo habilis and Rudolfensis sometimes are included with the Australopithecines - They also had more ape-like forelimbs but had larger brain-size than the Australopithecines.
For which hominids do we start to see a shift of more human-like morphology? What traits?
There is a change in anatomy in Ergaster/Erectus (1.89 MYA) post-cranially:
- Increased body-size
- Adapted to warm climate : Short arms, longer legged
- Running–long distance bipedalism
- Decreased dimorphism
- Probably slower development of young
- Increased home-range
The energetic costs of maintaining enlarged body and brain size suggest the occurrence of a shift to a higher-quality diet, some part of which likely included increased emphasis on meat and marrow acquisition. They still had mode 1 technology though.
The Dmanisi individuals are unique in their morphology, why?
The Dmanisi individuals (excavated in modern day Georgia) are dated to 1.7/1.8 MYA (some of the oldest Homo fossils outside of Africa). They exhibited a morphology that looks like a mosaic of earlier hominins and modern humans, the cranium and leg morphology were similar to H. erectus but were much shorter post-cranially and their brain size was much smaller (545–775 cm3) at least for the majority of the five recovered skulls, both of which are more comparable to H. habilis (Africa) than to later H. erectus.
The nomenclature of these individuals are debated, but they are likely a population of early H. Ergaster that left Africa before mode 2 tools came around.
What is the difference between H. ergaster and H. erectus which are often mentioned interchangeably?
H. erectus is what biologists call a chronospecies, a species that changes through time. Homo ergaster is the name given to its earlier phase, which lived mainly in Africa; the later Homo erectus lived mostly in Eurasia.
It was long thought that mode 2 tools had a “western” spread, but a recent study have found conflicting evidence. What did this study find and what are the potential consequences of this?
We thought Homo erectus spread beyond Africa as far as eastern Asia by about 1.7 million years ago. But, in 2018, scientists dated new stone tools and fossils from China to about 2.1 million years ago, potentially pushing the Homo erectus migration to Asia back by 400,000 years (Nature, Smithsonian).
There have been several early hominid migrations out of Africa, which species and when?
- Homo erectus is considered the first hominid species to migrate out of Africa ~1,7-1,8 MYA (although new evidence could push this date back as far as to 2,1 MYA).
- The second early migration out of Africa was the Homo Heidelbergensis expansion starting ~800 kya.
- There is also evidence of H. Sapiens migrations OOA before the major Out-of-Africa migration that lead to the spread of modern humans worldwide. One OOA c.130 000-80 000 BP - only to the Levant (current day Israel/Lebanon/Syria) = environmentally like Africa (and close).
Describe H. Heidelbergensis.
H. Heidelbergensis had morphology similar to H. ergaster, but more robust. They were expanding out of Africa already 800 000 years ago and was the first early human species to live in colder climates; their short, wide bodies were likely an adaptation to conserving heat. It lived at the time of the oldest definite control of fire and use of wooden spears, and it was the first early human species to routinely hunt large animals. This early human also broke new ground; it was the first species to build shelters, creating simple dwellings out of wood and rock.
H. Heidelbergensis were the first true Europeans and are sister group to Neanderthals, there is mtDNA from these dudes, they eventually proved to be Neanderthal/Denisovan ancestors (and H. sapiens).
Describe mode 3 tools, which hominid species is associated with them?
Mode three tools are similar to mode 2, but instead of preparing the core as the main tool, there is platform preparation - called prepared core technique - where the goal is to prepare the core in a way that made it possible to finally produce a flake of desired morphology –> Intended flake the main tool.
The mode three tools are associated with Homo sapiens and Neanderthals (360,000 - 45,000 ya) who have a morphology similar to that of H. Sapiens but more robust. In fact, morphology of Neanderthals is found within variation of Homo sapiens but the combinations of these traits are unique to Neanderthals. Homo Naledi (335,000-236,000) could also potentially have produced mode 3 tool based on their hand morphology and presence time.
Describe Mode 4 and 5 tools.
Mode 4/5 tools are characterized by core prepared for production of even formed blades through pressure techniques. Standardized morphology and kind of beautiful - required a lot of practice and honing of skills to make.
Mode 4: Long Blades (Upper Paleolithic - roughly 50,000 to 10,000 years ago).
Key Features: Long, thin stone blades shaped into various specialized tools like knives, spearheads, and burins. Marks the widespread use of blades rather than just flakes, indicating increased precision and specialization in toolmaking.
Mode 5: Microliths (Later Upper Paleolithic and Mesolithic - 15,000 to 10,000 years ago). Key Features: Tiny stone blades or flakes (microliths) often used in composite tools. Indicates the development of composite tools, where smaller components were combined to create more complex and versatile weapons and tools. Examples include arrowheads, sickles, and other specialized implements. Microliths were often attached to bone or antler handles using adhesives like tar or honey and used for hunting, woodworking, food preparation, and other tasks.
Mode 4-5 appears together with many cultural elements (images, fishing tools etc.). This does not seem to be gradual but more of a sudden change.
Many hominids where present at the same time as H. sapiens, which?
Many other species were present: Neanderthals, Denisovans, Homo floresiensis, Homo luzonensis and maybe more. Evidence suggest that we had contact with many other hominid species.
When did the ancestor of all placental mammals likely appear?
Results suggest that the ancestor of all placental mammals evolved less than 400,000 years after the mass extinctions that wiped out the dinosaurs, so about 65 MYA.
The hypothetical creature, not found in the fossil record but inferred from it, probably was a tree-climbing, insect-eating mammal that weighed between 6 and 245 grams—somewhere between a small shrew and a mid-sized rat. It was furry, had a long tail, gave birth to a single young, and had a complex brain with a large lobe for interpreting smells and a corpus callosum, the bundle of nerve fibers that connects the left and right hemispheres of the brain.
What is the inferred age of the common ancestor of all apes and monkeys?
The inferred age of the common ancestor of all apes and monkeys is 40 MYA, this is what is used as calibration.
