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Earlier notes have been archived. What follows are notes from Fall Semester, 2002. I have changed the dates of lectures to this semester, but we may not cover exactly the same material on that date. I may change these notes slightly after each lecture. These notes cover material which will be on the third exam.

Friday, March 14

    We began the discussion of Chapter 10 by discussing the span of time this chapter covers. It is the period from 5 million to 1 million years ago and covers all of the Pliocene and the first half of the Pleistocene, hence the term, Plio-Pleistocene. Early hominids were bipedal, and this form of locomotion required anatomical changes. The human foot has lost its opposable toe, and the arch in our foot helps absorb shock and adds a propulsive spring. Modern humans have relatively longer legs and shorter arms than apes, again an adaptation to bipedal locomotion. The human pelvis is broader and flatter than an ape's, and our gluteus maximus (the muscle forming your rear end) is attached differently to facilitate running and walking. The human spine is curved to keep the upper body centered over the pelvis, and our foramen magnum (hole in the skull for spinal chord) is repositioned under the head.
    The earliest hominids for which we have a good sample come from Ethiopia (Aramis) and are dated at 4.4 million years old. Paleoecologists infer that they lived in a woodland environment. The foramen magnum is in the hominid position, suggesting bipedal locomotion. Thin enamel on the molar teeth is a primitive trait, reminiscent of Miocene hominoids. For this reason some taxonomists have suggested that these early hominids should be placed in a separate genus and species: Ardipithecus ramidus.
    The next hominid form we discussed is poorly known. It dates to about 4 million years ago and is called Australopithecus anamensis. It has thick enamel on its molars, and its leg bones provide direct evidence of bipedalism. Better known is Australopithecus afarensis which comes from Hadar (in the Afar triangle of Ethiopia) and Laetoli.   The time range for this hominid is approximately 3.9 million to 3 million years ago. The foot prints in volcanic ash at Laetoli (uncovered by Mary Leakey) are evidence of bipedal locomotion and are dated by K-A (potassium - argon) to approximately 3.6 million years ago. The fairly complete hominid fossil nicknamed "Lucy" found by Don Johansen and his team at Hadar is an Australopithecus afarensis.
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Monday, March 24

    We began class by reviewing information on three early hominid taxa: Ardipithecus ramidus (4.4 million), Autralopithecus anamensis (4 million), and Australopithecus afarensis (3.9 - 3 million). A newly named taxon which we discussed for the first time today is Australopithecus garhi, dated at about 2.5 million years. The proximity of butchered animal bones to the remains of A. garhi provides indirect evidence of tool use. So far the earliest dated tools are about 2.5 million years old
    We then mentioned a few specimens from East Africa that have been termed "robust". They tend to have a large bony ridge on the top of their skulls called a sagittal crest. They also have large molars and pre-molars. It is believed that they were eating tough foods like seeds and nuts. The most famous of these is the fossil named Zinjanthropus by Louis Leakey at Olduvai. It is now know as Australopithecus boisei. Its nickname is "Nutcracker Man", because of its big back teeth (molars and premolars).
    "Robust" australopithecines are forms with small brains, large faces, large molars and premolars. Males often have a sagittal crest, which serves as an attachment for chewing muscles. The earliest example of a robust Australopithecine is Australopithecus aethiopicus dated at 2.5 million from East Africa. Later examples are Australopithecus boisei (Zinjanthropus) from East Africa and Australopithecus robustus from South Africa. These latter two forms are roughly contemporaneous, but occupy different geographical areas.
    The first Australopithecines to come to light were all from South Africa. It was Raymond Dart, an anatomist, who named the first Australopithecine. Back in 1924 he called the fossil he studied Australopithecus africanus. Australopithecine fossils from South Africa come from limestone breccia, a cement-like matrix. Raymond Dart thought that the South African Australopithecines ( A. africanus and A. robustus) were killer apes. More recent taphonomic studies suggest that the fossils we have of these South African hominids may have been the remains of leopard meals. In short, they were the hunted, not the hunters.
    A year after Louis Leakey found Zinjanthropus (now called Australopithecus boisei) at Olduvai, he found fragments of a more advanced hominid. He called these remains Homo habilis (handy man in Latin). Leakey called the fossil "handy man" because he believed that this form was the tool maker at Olduvai, not Zinjanthropus. Early members of our genus (Homo) had bigger brains (greater encephalization) than the Australopithecines.
    An important implication of these discoveries is that there was a more advanced form of hominid around at the same time that there were "robust" Australopithecines. This would make the robust australopithecines "side branches" on our family tree, since we are likely descended from more advanced forms like Homo habilis.

Wednesday, March 26

    We began by reviewing the various hominid taxa we have covered in Chapter 10. They appear below.
Ardipithecus ramidus    4.4 m
Australopithecus anamensis   4m
Australopithecus afarensis      3.9 - 3 m
Australopithecus africanus      3 - 2.3 m
Australopithecus garhi             2.5 m
Australopithecus aethiopicus   2.5 m
Australopithecus robustus        2 - 1.3
Australopithecus boisei       2.3 - 1 m

All of the above were found in Africa. Australopithecus africanus and Australopithecus robustus were found in South Africa, the rest were found in the East African Rift Valley. You should know that these are all Plio-Pleistocene hominids dating between 5 m - 1 m years ago, but don't worry too much about the exact dates. You should know that the first three listed above are early hominids. The "robust" australopithecines are A. aethiopicus, A. robustus, and A. boisei. Some of the "robust" forms coexist with more modern hominids, namely Homo habilis and Homo erectus. There is not agreement on hominid phylogeny. Often, it comes down to a debate between "lumpers" (those who emphasize similarities) and "splitters" (those who emphasize differences).

Taphonomic studies of Australopithecine localities in S. Africa suggest that at least some of the hominid remains were deposited there as a result of having been eaten by leopards. When we talk about the faunal remains associated with Homo habilis, it appears that this hominid was scavenging the kills of predators. This also was seen in the video.

Homo habilis existed from approximately 2.4 m - 1.6 m. Homo erectus existed from approximately 1.8 m - 200,000 years ago. Some populations of Homo habilis probably evolved into Homo erectus. Dating of fossil material from this period is imprecise, so the overlap in time between these forms may not be real. Homo erectus is found in Africa, S. Europe, and Asia. It appears to have been the first hominid to leave Africa. The body size of Homo erectus is larger than Homo habilis. The cranial capacity is also larger, with Homo erectus having an average cranial capacity of around 900 cm³. Next time we will discuss Homo erectus in more detail. . The cranial shape of Homo erectus differs from a modern skull in the following ways 1) large brow ridges (supraorbital tori), 2) a nuchal torus (on back of skull), 3) receding forehead, and 4) a long low skull which is widest at its base.

It was Eugene Dubois, a Dutchman, who found and described the first specimen on the island of Java. Dubois called his find Pithecanthropus erectus (erect ape-man), but today it is considered to be Homo erectus.

Friday, March 28

We began by reviewing the age and distribution of Homo erectus More fossils came from China in the 1920's and 30's. They were from the cave of Zoukoudian, which is near modern Beijing. Today it gets cold in this region in winter and paleoecologists feel the same was true when Homo erectus was there. From this, we infer the use of clothing and probably fire.. Of the more than 40 individuals identified from Zhoukoudian, only one lived past the age of 50. In the 1980's an important Homo erectus fossil was found at Nariokotome, a locality near Lake Turkana in East Africa. It is a nearly complete individual dated to 1.6 million years ago. The skeleton was of a young boy, and if he had reached adult stature he probably would have been around 6 feet tall.

Some taxonomists note that the African specimens have thinner cranial bones and other differences from the Asian specimens. They have proposed that the African forms be called Homo ergaster. This is not yet widely accepted.

Homo erectus in Africa, S. Europe and western Asia made Acheulean hand axes. These stone tools are more sophisticated than the earlier Oldowan hand axes made by Homo habilis. In particular, Homo erectus was able to drive off thin flakes using a soft hammer like bone or antler (something softer than stone). This allowed them to make an axe with a straighter edge. It is not clear why populations in the Far East did not have this technology. Perhaps they were using bamboo. Also, there is a possibility that they were a different species (Homo erectus vs. Homo ergaster).

In class, the following functions of fire were discussed: warmth, cooking, fire-hardening wood, heat treating flint, protection, and light. Hominids living in northern areas must have relied on fire for warmth, and it is assumed that they were capable of making fire.

Perhaps the most striking trend in hominid evolution is the gradual increase in brain size. Roughly paralleling this trend is a gradual increase in the sophistication of stone tool manufacture and other technologies such as mastery of fire. There is also increasing evidence through time of increased hunting ability on the part of hominids. The simplest explanation for increased brain size is that it is the result of natural selection. Those individuals or populations that were better able to master technology, effectively hunt and communicate must have had a higher fitness than those individuals or populations with smaller brains who were unable to effectively hunt, communicate, or utilize technology. Put most simply, there was selection for intelligence. The price that we pay for bigger brains is that infants must be born before their brains get too large, because giving birth to large headed babies is difficult. Human infants are thus more helpless than ape or monkey infants, and require more care. At some point in human evolution, we assume the development of what we would recognize as a family: a male-female pair and offspring. The possible development of a division of labor (male hunting, female gathering) and helpless infants would have encouraged this. Perhaps by the time of Homo erectus hominid females no longer came into estrus.

Chapter 12 discusses members of our genus and species that lived between 400,000 - 35,000 years ago. Because these hominids had some traits resembling Homo erectus, we refer to them as archaic Homo sapiens. The Homo erectus - like traits include thick cranial bones, big brow ridges (supraorbital tori), and a low skull. More modern traits include the average cranial capacity which is around 1200 cm³, which is larger than the 900 cm³average of Homo erectus.

Monday, March 31

At the site of Atapuerca in Spain, the bodies of at least 29 individuals were thrown down a vertical shaft at the back of a cave. This is the earliest evidence that we have of deliberate "disposal" of dead hominids. The later Neandertals were the first to deliberately bury their dead. Culturally, archaic Homo sapiens had the prepared core or Levallois technique for manufacturing flakes. This technique shows planning on the part of the tool maker. Artificial shelters are being used at this time, and there is good evidence of deliberate hunting. Some well made spears dating to almost 400,000 years ago have been found in Europe.

The place of Neandertals in hominid phylogeny remains a contentious issue. Neandertals are found in Europe and the Middle East and they lived from approximately 130,000 - 35,000 years ago. Our text considers them to be a variety of late archaic Homo sapiens. Technically, this view is reflected in the taxon, Homo sapiens neanderthalensis. Others see Neandertals as a separate species, and refer to them as Homo neanderthalensis. What taxon you use determines your view of their place on our family tree (hominid phylogeny). Neandertal skulls were large, and their cranial capacity averaged 1520 cm³which is larger than the average for modern humans (1300 - 1400 cm³). Neandertals had big brow ridges and what is called mid-facial projection. It is as if middle part of their faces were pulled forward.

A Neandertal skull was discovered in the Neander Valley (thal is the old German spelling for valley) in 1856. A reconstruction of a Neandertal skull in the early part of the 20th century portrayed Neandertals as hunched over and shuffling along. Unfortunately this picture was based on the skeleton of an individual who had a degenerative bone disease. Today we know that healthy Neandertals stood and walked the way we do.

After reviewing Neandertal skeletal features, I discussed the discovery of "the old man" from La Chapelle (France). He had a cranial capacity of 1620 cm³and suffered from osteoarthritis. He was about 40 years of age. It is this skeleton that gave rise to the incorrect notion that Neandertals did not walk upright. Significantly, he was buried in a flexed position with what are believed to have been grave offerings - tools and animal bones. He represents one of many Neandertal burials.

Neandertals disappear from the fossil record between 35,000 - 28,000 years ago. One of these last Neandertals, the fossil from St. Cesaire, is associated with Upper Paleolithic tools from the Chatelperronian culture. It used to be thought that only modern humans made these kinds of tools.

Neadertals are also found in western Asia. Tabun and Kebara Caves are located in Mt. Carmel in Israel and Shanidar is found in Iraq. Pollen from around a Neandertal burial at Shanidar suggests offerings of wild flowers. The easternmost Neandertal comes from Uzbekistan (site of Teshik Tash).

The stone tool culture of Neandertals is called Mousterian, and it is considered to be a Middle Paleolithic culture. Up to now, all the stone tool cultures we have studied (Oldowan, Acheulean, Levalloisian) have been considered Lower Paleolithic. Don't confuse Paleolithic (a cultural period) with Pleistocene (a geological epoch). Both are subdivided into Upper, Middle, and Lower, but each covers a different time span. Lower Paleolithic tools were made during the Lower, Middle, and Upper Pleistocene. The Mousterian is characterized by many different kinds of flake tools. This illustrates increasing specialization of the tool kit.

Neandertals lived in open sites as well as caves and rock shelters. They depended on hunting. They often buried their dead and they took care of sick and aged individuals, as evidenced by the individual from La Chapelle and a crippled Neandertal from Shanidar. Neandertal bone fractures show the same pattern as that seen in modern rodeo riders, suggesting close encounters with large animals. They had their darker side, as there is good evidence of cannibalism. Some Neandertal skeletons show cut marks and processing in a fashion similar to game animals.

Wednesday, April 2

Today we reviewed the above material for the exam on Friday. Reviews on Wed. at 2 and Thurs. at 12:15, both in the Classroom B-166.