In this chapter students will learn:

• the basic methods, concepts, and issues of palaeoanthropology.
• about the nature of the human fossil record.
• ideas about why the bipedal adaptation may have emerged.
• about the biological changes that occurred to allow efficient bipedalism.
• the genus and species of fossil humans over the last several million years.
• about the general trends in human biological evolution.
• that race is not a valid biological category.

Introduction
Human evolution took place over millions of years. Multiple human genera and species have existed, many at the same time.

Palaeoanthropology – Methods, Concepts, and Issues
Anthropologists typically look for early human sites where sediments of the time period of interest are exposed. There are multiple ways of dating sites, including Potassium/Argon dating. Some anthropologists are lumpers; others splitters.

Defining Hominins
There is no consensus definition of human or hominin, but it is common to accept that it includes all taxa with evidence of bipedalism that have emerged since the split from the common ancestor of humans, chimpanzees, and bonobos.

Becoming Bipedal
There are multiple potential reasons why our ancestors became bipedal. Many focus on the notion that walking on two legs frees the hands to carry things, such as babies, food, and tools. Becoming efficiently bipedal requires several evolutionary changes in the human skeleton.

The First Hominins
The best candidates for the first hominin include Sahelanthropus, Orrorin, and Ardipithecus, but there is no consensus due to the few numbers of specimens found. Other early hominins include Australopithecus (and for splitters, Paranthropus and Kenyanthropus).

The Genus Homo
Homo emerged between 3 and 2.5 million years ago in Africa. There have been several species of Homo in Africa, Asia, and Europe, with lumpers and splitters debating the exact number of species.

Summary of Trends in Human Biological Evolution
Trends include increasing proficiency at bipedalism, larger bodies, larger brains, more vertical foreheads, flatter faces, and smaller teeth. More recent trends include lighter and finer body hair and lighter skin in Europe and Asia.

The Concept of Race
There is no biological support for the concept of race. Human variation does not cluster into racial categories.

1. What are the basic methods, concepts, and issues in palaeoanthropology?

2. What are the principal explanations for becoming bipedal and the skeletal changes that accommodated it?

3. What are the widely recognized genera and species of humans?

4. Why is race not a valid biological category?

1. How can basic evolutionary concepts such as mutation, gene flow, genetic drift, and punctuated equilibrium be applied to human biological evolution?

2. What are some of the advantages and disadvantages of having no fixed criteria for assigning specimens to a specific genus or species?

3. What are possible explanations of the relatively small size of Homo floresiensis and Homo luzonensis? Were they likely descended from Homo erectus, or some other species? Can their small size be attributed to island dwarfism, or something else?

dating by association dating artifacts and sites by their association with other artifacts, ecofacts, or geological features of known age

dental arcade the shape of tooth rows, such as parabolic (wider at back than front) or u-shaped

diastema a space between teeth

foramen magnum the hole at the base of the skull, through which the spinal column enters the brain

fossil in anthropology, a term used to describe any preserved early human bones or teeth

fossil record in anthropology, the assemblage of early human remains, or the interpretation of human evolution based on human remains

Great Rift Valley an area in East Africa where many important palaeoanthropological sites are located

potassium argon dating dating technique based on measuring the ratio of potassium and argon in volcanic sediments

prognathism having a protruding face

radiocarbon dating dating technique based on measuring how much carbon 14 is in preserved organic remains

savannah an environment common in tropical and subtropical Africa, consisting of wild grasses and sparse tree growth

taphonomy the study of what happens to organic remains after death

Berger, L., et al. (2015). Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa. elife 2015;4;e09560. DOI http://dx.doi.org/10.7554/elife.09560.

Dawn of Humanity (video). (2015). Nova and National Geographic Studios for WGBH Boston.

Fuentes, A. (2012). Race, Monogamy, and Other Lies They Told You: Busting Myths About Human Nature. Berkley, CA: University of California Press.

Goodman, A.H., Moses, Y.T., & Jones, J. L. (2012). Race: Are We so Different? Malden, MA: Wiley-Blackwell.

Zuk, M. (2009). Paleofantasy: What Evolution Really Tells Us About Sex, Diet, and How We Live. New York, NY: Norton.

American Museum of Natural History, Hall of Human Origins
amnh.org

Becoming Human (Institute of Human Origins at Arizona State University)
becominghuman.org

Leakey Foundation
leakeyfoundation.org

Skeleton Project
eskeletons.org

Smithsonian National Museum of Natural History – What Does it Mean to be Human
humanorigins.si.edu

Understanding Race
understandingrace.org

1. If you encountered a site that you presumed to be 40,000 years old, which dating method would you prefer to use and why? Then, if you discovered more remains of a species of mammal known to be extinct for over 75,000 years, would your choice change?

2. What advantages did our ancestors have by becoming bipedal? What advantages did they lose by becoming bipedal?

3. Imagine an alien came to Earth and wanted to understand how humans categorize themselves. How would you explain it?

4. What are some of the problems with the concept of race and using DNA to test ancestry?

5. Summarize the various physical changes that were necessary for, and/or occurred as a result of, bipedalism.

6. How does the anthropologist’s definition of “fossils” compare to other meanings of the word, and what other areas of study assist fossil research?

7. If someone found evidence of human activity from one million years ago, what might you expect they found?

8. What are some of the uncertainties surrounding the existence of the first hominins?

9. What would be significant about someone finding a full skeleton of a Homo ancestor dating 2.5 million years ago?

10. Compare any assumptions you had about Neandertals (e.g., from pop culture, etc.) with what you now know about their likely realities.

Answers

1. Your answer should demonstrate comprehensive understanding of the three main methodologies used to date sites and remains, and their relative advantages and disadvantages depending on the situation. You should also keep in mind that, whenever possible, it is normal and desired practice to use as many methods as possible at one time.

• Potassium argon dating, often abbreviated K/Ar, would not be a good method for the first scenario because it is generally considered to be the best technique for determining the age of sites over 200,000 years old. Since the process of changing from potassium to argon is very slow, this is not a useful technique for sediments more recent than a few hundred thousand years.
• Likely, you would want to first use radiocarbon dating, also known as Carbon 14 or C14 dating, as it is the best technique for determining the antiquity of sites assumed to be less than 50,000 years old (assuming no written records exist). This method is not reliable over 50,000 years because there wouldn’t be enough carbon left to date in any found organic material, and so it would not likely help you if the site is actually 75,000 years old.
• Through Dating by Association in the second scenario, you base your dating on the fact that if two things are found in the same stratigraphic layer, and the antiquity of one object is already known, then the other object is probably the same age. Since K/Ar dating would still not be an option for the age of the site, this method would then likely be the foundational method for the second scenario.

See pages 86-87 of your text.

2. Your answer can include things not listed here, but should note at least some of the following:

• Advantages include
• freeing up the hands, to create tools and carry things.
• being taller, and so appearing more threatening to predators, as well as seeing further.
• effective heat management and/or greater endurance abilities.
• Disadvantages include
• being more vulnerable, and so easier to see by predators, with limited speed.
• enormous amounts of stress on the skeleton.

See pages 88-92 of your text.

3. Answers should explain how classification systems are essentially artificial constructs created by humans to make sense of their world.

• Even humans do not collectively agree: the lumpers vs. splitters debate.
• It can depend on what features are emphasized (dental arcades, skeletal configurations, brain size, etc.).

See pages 87-88 of your text.

4. Answers should explain that race is not a biological category and the ancestry testing marketed to the general public is flawed, especially in suggesting links to populations.

See pages 102-104 of your text.

5. The answer should demonstrate a familiarity with the overall changes that occurred (and an understanding of which are cause and which are effect). The specific changes that had to occur to facilitate bipedalism include:

• repositioning of foramen magnum
• changes to the vertebral column (adding curves)
• changes to the pelvis (widening, basin shaped, stabilizing weight distribution)
• lengthening of femur (increased stride length)
• modification to knee (allowing knee full extension and to lock in place)
• angling of femur inward
• changes in the foot (e.g., arch, re-alignment of big toe)

The brain also became larger, but this is a result of bipedalism rather than something that had to occur for bipedalism to become possible.

See pages 88-93 of your text.

6. Answers should include:

• The word “fossil” is applied very loosely in anthropology. For some, it means that the organic remains have turned into stone, or left an impression in stone, but this is not the case in anthropology. In anthropology, “fossil” is used to describe any preserved early human remains, no matter their condition. Thus, when one speaks of human fossil remains, it simply means they exist, and may be in an extremely soft or fragile state.
• The “human fossil record” has multiple meanings. In one sense, the fossil record may be taken to mean the interpretation of human evolution, based on the data of the collected remains. In another sense, the fossil record may be taken to simply mean the assemblage of bones collected.
• Taphonomy and osteology fields can assist fossil research, as can the various dating techniques used to date sites.

See pages 81-83 of your text.

7. This answer could encompass many things, but should include justification for the choices made.

• Depending on the area where it is found, remains could be well preserved or not well preserved. For example, a buried skeleton or remains found near a lake might preserve very well.
• Teeth or a mandible could be likely, as they are the most commonly found skeletal fragments for human remains.
• Artifacts or remains found in a cave could be likely, as caves preserve things well (by protecting from severe scavenging and decomposition).
• Things like organic matter would likely not be found, and a full skeleton would also be unlikely.

See pages 83-88 of your text.

8. Answers should include:

• The precise date at which they emerged, as there is no consensus with respect to the definition of “human” or “hominin.” Many consider hominins to include all members of the genus Homo and other taxa with evidence of bipedalism that have emerged since the split from the common ancestor of humans, chimpanzees, and bonobos about 7 million years ago.
• When and why they became bipedal.
• Exactly which species fit into the hominin category (e.g., Sahelanthropus, Orrorin, and Ardipithecus).
• Which Australopithecine likely evolved into the first species of Homo (the primary contenders are afarensis and africanus).

See pages 83–86 and 93-94 of your text.

9. The answer should identify why all of these components together are an unlikely combination, as well as explain the significance of their existence together.

• Human remains do not preserve equally, and it is extremely unlikely to find such an old, complete skeleton. More likely, only the teeth and/or mandible could be found, as they are densest and preserve better. Remember, the entirety of the human fossil record could likely fit into a dump truck.
• The preservation of human remains prior to deliberate burial practices (being unintentionally covered by the ground and not exposed to deteriorating circumstances), before 50,000 years ago, is rare.
• The oldest undisputed skeletal remains date to about 2.2 million years ago, but most anthropologists believe they probably emerged about 2.6 million years ago, and we just haven’t found the skeletal evidence yet. A 2.5-million-year-old find would be extremely fortuitous and could provide immense knowledge about this uncertain time.

See pages 81-83 and 93-94 of your text.

10. This answer can vary depending on one’s personal experiences but will likely include reference to Neandertals being big, dumb, hairy cave-dwellers. The realities of who they were include the following:

• They were typically rugged, with prominent brow ridges, large noses, and powerful limbs. Their average cranial capacity, at 1,450 cc is about 100 cc larger than the average among modern populations.
• Their body type is often described as being short and stocky, similar to that of contemporary Inuit. In a similar vein, the body type was probably an effective adaptation to the cold. It is estimated that when Neandertals were living in Europe, the temperature was an average of 10° Celsius colder than present.
• Neandertals were adept tools makers, had a diverse diet including many kinds of animals, used spears, and controlled fire.
• Neandertals probably hunted effectively with throwing spears, cooked their food, wore clothing (not tailored), and used speech as their primary means of communications.
• Many believe that for the last 100,000 years, they could probably speak as well as modern humans.

See pages 98-100 of your text.

1. Why would it be necessary to specify that the presenter of an upcoming talk on fossils is an anthropologist?

• a) Many people find anthropological talks controversial and they need to be given warning beforehand.
• b) Fossil studies are almost exclusively conducted by geologists, and thus it is quite unusual to have an anthropologist presenting on this topic.
• c) Although other disciplines may define fossils in relation to stones, this presenter is referring to some preserved early human remains.
• d) So that the audience will know that they cannot ask questions about anything other than the specific fossils

2. If I called you a “lumper,” that would mean

• a) you believe that fewer taxonomic categories exist and that considerable variety can occur within genera and species.
• b) you believe there is little variability within genera and species and therefore posit many different categories.
• c) you do not believe that K/Ar dating (potassium argon dating) can accurately pinpoint the age of remains and sites past 500,000 years.
• d) you study mounds and other conspicuous sites that jut out of the ground (i.e., lumps).

3. If you were conducting a dig hoping to find human remains, which of these sites would be most likely to yield good findings?

• a) An area with a record of good preservation of organic remains, such as a cave.
• b) An area chosen through a random algorithm somewhere in West Africa.
• c) An area where sediments (from the time period you’re looking for) have remained fully covered.
• d) An exposed area where many scavengers have lived.

4. If you found human remains at a site, what type would they most likely be and why?

• a) The mandible, including teeth, because it is the thickest and most dense bone of the skeleton.
• b) The metacarpals, because there are many of them in every skeleton and therefore at least one has a better chance of being found.
• c) The cranium, because it protects the brain and is therefore the most important part of our skeleton.
• d) The pelvis, because it is from the pelvis that biological sex can often be determined.

5. If someone injured their phalanges, they probably wouldn’t be able to

• a) tell a story.
• b) go salsa dancing.
• c) stand on one foot.
• d) use a typewriter.

6. The best method for dating sites over 200,000 years old would be

• a) C14 (radiocarbon) dating.
• b) K/Ar (potassium argon) dating.
• c) Dating by Association.
• d) taphonomic exclusion.

7. Anthropologists believe that humans are

• a) not innately and immutably aggressive, but neither are we aggression-free.
• b) inherently aggressive, much like what is witnessed in chimpanzee behaviors.
• c) inherently driven toward societal cohesion, avoiding conflict.
• d) not unusual, in that violence is the natural order of things.

8. Which of the following changes to the skeleton did not occur in order to facilitate bipedalism?

• a) Vertebral column curvatures.
• b) Centrally aligning the foramen magnum.
• c) Flatter foot arches.
• d) Femurs angling inward.

9. The labels erectus, ergaster, georgicus, antecessor, and heidelbergensis refer to

• a) hominins belonging to the Paranthropus grouping, representing approximately 3.5 million years ago to 1 million years ago.
• b) hominins belonging to the Middle Homo grouping, representing approximately 1.7 million years ago to 200,000 years ago.
• c) likely hominins belonging to the Early Contender grouping, representing approximately 7 million years ago to 4.4 million years ago.
• d) hominins belonging to the Australopithecines grouping, representing approximately 4.2 million years ago to 1.8 million years ago.

10. The concepts of race and species are similar in that

• a) they are both concrete and uncontroversial terms (everyone agrees on these categories).
• b) they are both very recent ideas which have only developed in the last 100 years.
• c) they are both invented concepts, not actually being “natural” categories.
• d) they are both proven through evolutionary understandings, though definitions vary.

Answers

1. c

Feedback: The word “fossil” is applied very loosely in anthropology. For some, it means the organic remains that have turned into stone, or left an impression in stone, but this is not the case in anthropology. In anthropology, “fossil” is used to describe any preserved early human remains, no matter their condition. Thus, when one speaks of human fossil remains, it simply means they exist, and may be in an extremely soft or fragile state.

See page 81.

2. a

Feedback: Lumpers tend to assume there is considerable variability within genera and species and therefore tend to have relatively few taxonomic categories for the several million years of human evolution. Splitters, on the other hand, tend to assume there is relatively little variability within genera and species, and therefore tend to recognize many different genera and species over the millions of years.

See page 83.

3. a

Feedback: When in caves, bones are often protected from the normal elements leading to decomposition, whereas random sites do not produce as good chances as known sites; sediment exposure helps researchers find the eras they are looking for, and scavengers are a detriment to finding remains.

See pages 82-83.

4. a

Feedback: Not all human remains preserve equally. Teeth tend to preserve the best, followed by the bones of the skull. The mandible (lower jaw) is the thickest and most dense bone of the skeleton and thus preserves the best of all the bones, and is sometimes found with the teeth intact. All the bones beneath the head, commonly known as the post-cranial bones, are preserved less often. Except for the mandible, bones are rarely discovered complete. They are typically highly fragmented, and pieces of bones are frequently missing. This is usually due to natural processes acting on the bones over the years since the individual died.

See pages 81-82.

5. d

Feedback: The phalanges are the finger bones, injury to which would make typing quite difficult. Dancing and talking would still be ok!

See page 84.

6. b

Feedback: Potassium argon dating, often abbreviated K/Ar, is generally considered to be the best technique for determining the age of sites over 200,000 years old. The basic principal of potassium argon dating is that when volcanic sediment (such as ash or lava) is hot (as it is when being expelled from the volcano), there is potassium, but no argon. As the sediments begin to cool, potassium begins to change into argon and we know that rate of change.

See page 86.

7. a

Feedback: There is no research showing that aggression is genetically based, and we share traits with both bonobos (who exhibit more passive and social behaviors) and chimpanzees (who exhibit more violent behaviors).

See pages 88-89.

8. c

Feedback: There are several skeletal changes that occurred to accommodate efficient bipedalism, and structural changes to the foot developed the arch.

See page 91.

9. b

Feedback: Adaptive radiation of the genus Homo has continued over the past million years. Some finds from Spain, classified as Homo antecessor, may be ancestral to more recent species, but the evidence is too meagre to lend confidence to this claim. Homo heidelbergensis appears about 700,000 years ago, overlapping in time with Homo erectus, and may have evolved from antecessor.

See pages 95 and 98-99.

10. c

Feedback: Race is a term that is used widely in North America, but there is often a misunderstanding that it is a natural or biologically based category. It is not. The category was invented, suggesting race is something akin to a subspecies, identified by a combination of physical and behavioral characteristics.

See pages 83 and 102-104.