Migration Answers

Migration Assignment

Here are the answers to the problem set for this week on migration patterns of hominins.  You needed to review that related readings and maps that accompanied this assignment in order to complete it.  There were 10 questions, with each question worth 4 points.

Questions:

1.   On which continent(s) has fossil evidence been found of one of our earliest ancestors, the Australopithecines? 

Fossil evidence of Australopithecines has only been found in Africa, primarily in the Rift Valley on the eastern continent but also in southern Africa in the area of Johannesburg.

2.   Of all of the species from the Homo genus represented on the map, which one does NOT have evidence of having migrated out of the African continent?

Only Homo habilis appear to have remained on the African continent as there is no fossil evidence anywhere else of this hominin.

3.    Identify and support two possible explanations as to why early hominids migrated out of Africa. 

The answers to this can be divided into two main categories of answers.

a.  Seeking opportunity:  Following migrating herds, better water supply, changing climate may have made northern and eastern territories more appealing.

b.   Escaping a threat:  Avoidance of predatory animals, leaving occupied territories for open ones (less competition), changing climate might have made some African areas inhospitable, avoiding devastation from natural disaster (e.g., volcanic).

4.   What type of vegetation is predominantly found in Northern Europe during this time period? 

The region of Northern Europe was dominated by tundra with some incursion of open woodland and forest.

5.   Which hominid ancestor was able to occupy the most northern areas of Europe? 

The most common fossil to be unearthed in the most northern areas of Europe were those of H. heidelbergensis, with Neanderthal being the next most northern.

6.   Identify three cultural adaptations which likely contributed to the hominid you identified in (b) being able to exist in northern Europe given its climate during this time period. 

Any adaptation that would have allowed them to live in a new and different climate would have been beneficial.  This includes warmer clothing, hunting animals with warmer fur to make that clothing, control of fire, residing in caves instead of out in the open, a new tool kit to make use of available resources more efficiently.

7.   What was the only hominid to migrate to Australia?  Speculate as to why no other hominid made it to this continent, including environmental conditions.  

H. sapiens were the only early hominin to migrate to Australia and that is because they were the only hominid in the region at that time, so they were the only ones able to take advantage of that migratory option.  There is debate upon how this might have happened given that Australia’s connection to the mainland would have been intermittent with the sea levels rising and falling.  It could have been that the timing of migrating H. sapiens was such that it coincided with a land bridge that permitted them to just walk to Australia.  Or H. sapiens might have had the cultural adaptations (such as early boats or rafts) to allow them to travel across relatively large bodies water, though this raises the question of WHY they would travel that way unless they knew ahead of time where they were traveling TO.  Understand that they didn't consciously wake up one day and say "We're going to Australia.".  They would have just followed herds of animals or other available resources.  They weren't moving TO somewhere... they were just moving.

8.   Given the evidence offered on both maps, which hominid most likely migrated into North American and identify when in our history this migration likely happened.  Explain.

Only fossils of H. sapiens have been found in the northern regions of Asia in what is now called Siberia around 14,000 ya, making them the most likely candidate for crossing the land bridge between Asia and North America.  This does not rule out other hominins from having made the crossing, but the fossil evidence does not support that at this time.

9.   How does this map support the general contention that Africa was the “cradle of human history”?  What evidence would you have to find to falsify this hypothesis? 

The earliest versions of our hominin ancestor, the Australopithecines, are located only in Africa.  Later groups have left behind fossil evidence of having existed in both Africa and elsewhere, indicating migration outward.  The timeline of fossil findings matches with the hypothesis of early origins in Africa with later migration out to other parts of the world. 

Falsification of this hypothesis would require finding evidence of these earliest hominids outside of Africa with a timeline suggesting movement out of that alternate area instead of Africa.

10. There are some areas globally where pockets of fossils have been found.  Does that mean hominids didn’t exist where we don’t find fossils?  Explain.  Offer two other explanations for why we haven’t found fossils in some areas. 

No, to assume that a lack of fossils means no fossils is to suggest that we have found all possible fossils.  Possible explanations for a lack of fossil information for particular areas can include:

(a)  Fossilization processes may not be amenable in certain areas and they may be lacking in the conditions necessary to produce fossils.

(b)  Population numbers of hominids may not have been large enough to produce a reliable supply of fossils.

(c)  High population numbers of scavengers and predators (which is likely in organically rich areas, such as tropical areas) may mean that potential fossil bodies are destroyed and eaten without the opportunity to fossilize.

 (d) Scientists may have not looked in those regions yet.