Megafauna Extinction & De-Extinction

Question 1

Which of the following statements correctly summarizes both the human overkill hypothesis and the climate‑change hypothesis for the extinction of Pleistocene megafauna, citing the key evidence used for each?

Accepted Answer

The overkill hypothesis notes that humans entered the Americas about 15,000 years ago and left stone tools and cut marks on megafauna bones, showing hunting pressure; the climate hypothesis points to rapid warming after the last Ice Age, documented by ice‑core temperature spikes and pollen records of shifting plant communities, which altered habitats.

Answer

The overkill hypothesis argues that a sudden asteroid impact killed megafauna, while the climate hypothesis claims that gradual cooling over thousands of years reduced food supplies, both supported by volcanic ash layers.

Answer

The overkill hypothesis states that megafauna died because humans introduced invasive plant species, demonstrated by pollen from non‑native grasses; the climate hypothesis says that solar flares caused abrupt temperature drops, indicated by solar activity proxies.

Answer

The overkill hypothesis suggests that ancient parasites spread by humans caused disease in megafauna, evidenced by fossilized parasite eggs; the climate hypothesis claims that rising sea levels flooded megafauna habitats, shown by marine sediment cores.

Question 2

Which statement most accurately combines the human‑hunting (overkill) explanation and the rapid‑climate‑change explanation for the loss of Pleistocene megafauna, and correctly cites the type of evidence that supports each hypothesis?

Accepted Answer

The overkill idea is backed by many sites where stone spear points and cut marks are found on extinct animal bones, while the climate idea is supported by pollen and ice‑core data that show a sudden warming and changing vegetation at the end of the Ice Age.

Answer

The overkill hypothesis cites the presence of large fire‑scars on the landscape, and the climate hypothesis points to ancient sea‑level rise records that flooded inland habitats.

Answer

The overkill idea relies on DNA studies that show close genetic ties to modern species, and the climate idea is based on the discovery of ancient volcanic ash layers that killed the animals.

Answer

Both hypotheses argue that humans introduced new diseases, a claim supported by fossilized parasites found on megafauna remains.

Question 3

A research team wants to bring back two extinct animals—the Irish elk and the thylacine—using modern genetic techniques. Which statement correctly lists the technical steps they must take and provides one scientifically valid argument supporting de‑extinction and one scientifically valid argument opposing it?

Accepted Answer

They must first recover as much DNA as possible, fill missing parts with DNA from the closest living relatives, edit that combined genome into the egg cell of a related species, and implant the embryo into a surrogate of that species. One supporting argument is that the revived animals could restore ecological roles they once played (e.g., grazing patterns of the elk). One opposing argument is that the original habitats no longer exist, so released animals could disrupt current ecosystems or fail to survive.

Answer

They should insert a few key genes from the extinct species into the genome of a modern relative and let natural breeding spread the traits. A pro argument is that the new hybrid could become a valuable source of food, and a con argument is that it might become an invasive species.

Answer

They can clone the extinct species directly by taking cells from the frozen specimen and using somatic cell nuclear transfer in an egg from a different order of mammals. A pro argument is that it will give scientists new insight into ancient DNA, and a con argument is that it raises animal‑welfare concerns for the surrogate.

Answer

They only need a well‑preserved frozen carcass and a surrogate mother of any large mammal; the surrogate will naturally give birth to a perfect copy of the extinct species. A pro argument is that increasing the number of species always improves biodiversity, and a con argument is that the project would be too expensive to be worthwhile.

Try three questions

Which of the following statements correctly summarizes both the human overkill hypothesis and the climate‑change hypothesis for the extinction of Pleistocene megafauna, citing the key evidence used for each?

Which statement most accurately combines the human‑hunting (overkill) explanation and the rapid‑climate‑change explanation for the loss of Pleistocene megafauna, and correctly cites the type of evidence that supports each hypothesis?

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