reading and answer questions 7
AFTER YOU GO OVER THESE NOTES, WATCH THE VIDEO LISTED BELOW, AND READ THE BOOK, ANSWER THESE QUESTIONS, WHICH YOU SHOULD EMAIL TO ME OR POST HERE ON CANVAS BY THIS COMING WEDNESDAY, MARCH 18:
1. How was Homo sapiens able to spread throughout the entire world, i.e. what where the physical and technological factors that made this species able to expand and thrive outside of Africa? 2. What might have happened to earlier species of Homo who were present in Eurasia and Africa before us? Give specific reasons for your answers.
Homo sapiens (our species) is just the newest design of a 2-legged primate model (hominins) that arose millions of years ago with the australopithecines and earlier species. What sets us apart from other hominins are our intelligence and our almost complete reliance on culture to interact with each other and with the environment.
Another unusual thing about our species is that we are the “last man standing†out of all the bipedal hominins that have existed. We are the only species in our genus, unlike the situation with, for example, horses, donkeys, and zebras, (all in the genus Equus—see https://www.amnh.org/exhibitions/horse/the-evolution-of-horses/meet-the-relatives (Links to an external site.) for the details).
Our singularity could be due to a number of factors:
- We out-competed the other contemporary hominins (Neanderthals, Denisovians, and others) for food, based on our more complex technology
- We bred the other species out of existence—this means we interbred with the earlier populations until they were absorbed into Homo sapiens populations with small amounts of their DNA remaining in the gene pool
- We killed them when we moved into their territories
- We brought diseases with us for which they had no resistance
- All of the above in different combinations in different parts of the world are, in my opinion, the most probable answer
At present, the oldest examples of Homo sapiens fossils are about 300,000 years BP (Before Present) from northern Africa. See page 136 in your book and https://www.nytimes.com/2017/06/07/science/human-fossils-morocco.html?module=Promotron®ion=Body&action=click&pgtype=article (Links to an external site.)
ANATOMICAL FEATURES of H. sapiens compared to other Homo species (see page 135 in your text):
- High and rounded braincase (large brains)
- Small face that does not stick out in the mouth area (this is called prognathism)
- Chins
- Small and separated (compared to earlier species) brow ridges (no uni-brows)
- Relatively narrow bodies
- Long growing times, i.e. we take longer to physically mature than earlier species. We probably also have a longer mental childhood (it takes us longer to reach mental maturity) but this cannot be seen in fossils.
Early Homo sapiens from about 300,000 to 100,000 BP show a lot of variations in skull shapes (see the graphic on page 137 in your text).
A composite reconstruction of the earliest known Homo sapiens fossils from Jebel Irhoud in Morocco based on micro computed tomographic scans of multiple original fossils. Credit…Philipp Gunz/Max Planck Institute for Evolutionary Anthropology
As you can see by comparing this reconstructed skull from Jebel Irhoud in Morocco to the one we studied in class, this skull looks much more rugged than the modern one. Modern skulls are more delicate and pedomorphic (pedomorphic means child-like, rounder). Thus, through either natural or sexual selection (or both), our facial appearances have changed over the past 300,000 years, especially after about 100,000 BP. This skull has a connected brow ridge (a uni-brow) and the lower part of the face does protrude but it has a chin and a large brain. So we can see that not all of the features that define modern humans developed at the same time.
TOOLS—MATERIAL CULTURE
We do not know about all of the tools that hominins, including early Homo sapiens, used because most of them have not been preserved. Tools made of bone, wood, or other plant or animal materials usually do not survive so we are left with tools made of stone (anthropologists call these tools “lithicsâ€). Read the discussion of the importance of stone tools on pages 89-93 again. Homo sapiens lithic tool kits relied on small flake tools made from prepared cores. These tools take skill and knowledge to produce.
Homo sapiens also developed an extensive range of bone and antler tools, many of which were probably used to work animal hides to turn them into leather to be made into clothes. They almost certainly used grasses and reeds and wood to make tools such as baskets or nets or rope or any number of other useful things but these have not been preserved in the archaeological record because they decayed.
SHELTER AND FIRE
As Homo sapiens groups moved out of tropical and subtropical Africa into colder climates in Eurasia, they had to find ways to keep themselves warm, especially at night. Some groups spent time in caves but others built shelters out of brush, animal hides, branches, or stone.
At least some groups of Homo erectus people knew how to control fire because they lived in cold climates. Homo sapiens and other later groups, such as Neanderthals and Denisovans and Homo Heidelbergensis, used fire for warmth and for cooking. Cooking hard vegetable food, such as tubers and roots, softens it and makes it easier to chew and to digest and often makes it taste better for us. Have you ever tried to take a bite out of a raw potato? It’s hard and it doesn’t taste very good plus your body could not get as much nutrition from the raw food as it can from the cooked version. Meat is also easier to chew if it is cooked. Foods could be cooked directly over a fire or could be buried in hot coals to roast. Later people learned how to boil food, which makes it easier to eat and digest, using stone boiling. Cobbles (small rocks) were put in a fire and when they were hot they were lifted out using sticks and put into water held a leather bag or a basket lined with clay to make it waterproof. The hot stones gradually heated up the water and whatever food had been put into the water. This was obviously not a quick cooking method but it worked. Later people learned how to suspend leather bags, and still later pottery containers, over a fire to boil food.
FOOD
People got food by hunting and gathering, they did not grow food or herd animals. People did not wander aimlessly over the landscape looking for food, they had a certain home territory within which they had a “seasonal roundâ€. A seasonal round is moving from place to place within a certain territory following the resources. Humans by the time of Homo sapiens were top predators, as are wolves, lions, etc., but perhaps the best analogy for us as hunters and gatherers are bears, because both bears and humans are omnivores (that means we eat everything, given the opportunity). However bears are not social and we as a species are social and we always have to think of getting enough food for the group, not just the individual. This is probably one of the reasons we have been so successful as a species – possibly those who did not think of others did not leave descendants.
How people got food depended on the environment where they lived and what sorts of resources were available. During the past 20,000 or so years in most environments, gathering brings in more calories than hunting but hunting usually has more prestige. Why do you think hunting has more prestige? This is not a formal question but you can give a written answer if you wish.
Gathering involves knowing where and when different foods are available in a group’s territory: when fruits ripen, where nut trees grow, where patches of cereal grass or nutritious roots can be found. Fishing can be done with nets or spears (remember the evidence from Kennewick Man’s arms). Shellfish (clams, oysters, etc.) can be gathered by wading into shallow water or diving. Hunting small game is often done with traps or snares. Hunting techniques for large game include one person stalking or lying in wait for an animal, small groups of men hunting a single large animal (bears, mammoths, etc.), or large communal hunts where all of the men, and probably the women and children, in the group take part in surrounding or stampeding and killing an entire herd of animals. Unless hunting is done by a single person it involves communication among the hunters, either in spoken language or gestures, and preplanning.
Depending on the resources available in their area, hunters and gatherers lived in small (from 5 or 6 to 50 or so) extended family groups. Bands may be loosely organized into tribes, based on family and marriage relationships. Tribes come together at certain times of the year when resources at one place are plentiful to 1. strengthen social ties through talking, eating, dancing, singing, and telling stories; 2. find marriage partners outside of their close family; and 3. exchange goods.
HOMO SAPIENS SPREAD THROUGHOUT THE WORLD:
Homo sapiens first left Africa about 100,000 BP via the Arabian Peninsula (page 139) but large scale migration probably did not occur until between 70,000 and 60,000 BP, based on genetic data. The genetic data shows that there is more genetic variability in Africa than in the rest of the world. This is because out of all of the variations in the human gene pool at that time (70,000 BP), only a limited number of people with their particular variants left and settled in other parts of the world (the “founder effect†that we discussed in class and that is on the Human Evolution handout you have). See the map on page 144.
When Homo sapiens left Africa they encountered other species of Homo that were descended from the same common ancestor, (possibly Homo antecessor or Homo heldelbergensis—see the chart on page 143), who had evolved separately in Eurasia: H. neanderthalensis, the Denisovans, and possibly others. Until about 40,000 BP, we were not the only humans in Eurasia, and likely also in Africa (Homo naledi, and possibly others, might have existed this late in Africa). In East Asia, other species, namely Homo floresiensis and Homo luzonensis, who are probably more closely related to Homo erectus than Homo sapiens, persisted. See https://www.sapiens.org/evolution/homo-luzonensis-discovery/ (Links to an external site.)
Homo sapiens, and earlier hominins, had home territories. They knew where to get food and find safety from predators within their territory. So why would they leave an area they knew very well to go to another place? Possible reasons include:
- Changes in the environment which changed the conditions in their home territory or opened up new areas
- Increasing population so the home territory did not have enough food for everyone
- Inter-group or inter-personal conflict
- Wanderlust (wanderlust is “a strong or innate desire to rove or travel about†https://www.dictionary.com/browse/wanderlust (Links to an external site.))
Watch the last episode of the NOVA show Becoming Human “Last Man Standing†(you have already watched the first episode). You can find it on YouTube at
https://www.youtube.com/watch?v=cLICJsmeby8&t=59s (Links to an external site.)
or on Amazon Prime https://www.amazon.com/Becoming-Human/dp/B003E48UME (Links to an external site.)
Some of the ideas presented in the video are out of date:
- The earliest Homo sapiens fossils are older than the ones mentioned in the video (see above about the fossils from Morocco)
- Neanderthals were not exclusively meat eaters. What they ate depended on where they lived. See https://www.sapiens.org/column/field-trips/neanderthal-diet/ (Links to an external site.) and https://www.sciencedaily.com/releases/2016/03/160314091128.htm (Links to an external site.) and https://www.nytimes.com/2008/09/23/science/23obfish.html?searchResultPosition=1 (Links to an external site.)
Here is an interesting short article about food storage by either Neanderthals or possibly an earlier Homo species https://www.nytimes.com/2019/10/09/science/marrow-israel-cave.html (Links to an external site.) “Sealed for millenniums, Qesem Cave in central Israel is a limestone time capsule of the lives and diets of Paleolithic people from 420,000 to 200,000 years ago. Inside, ancient humans [they mean hominins] once butchered fresh kills with stone blades and barbecued meat on campfires.â€
