Question

In 2017, Rogers, Bohlender, and Huff published a paper entitled Early History of Neanderthals and Denisovans. In this paper, they provide DNA evidence to support the hypothesis that Neanderthals and Denisovans diverged much earlier than previously thought (supporting “Hypothesis A” instead of “Hypothesis B” from this week’s lecture). Below is the authors’ summary of their paper:

Neanderthals and Denisovans were human populations that separated from the modern lineage early in the Middle Pleistocene. Many modern humans carry DNA derived from these archaic populations by interbreeding during the Late Pleistocene. We develop a statistical method to study the early history of these archaic populations. We show that the archaic lineage was very small during the 10,000 y that followed its separation from the modern lineage. It then split into two regional populations, the Neanderthals and the Denisovans. The Neanderthal population grew large and separated into largely isolated local groups.

Answer these

a. DNA extraction methods today are more reliable but are essentially the same sort of process. Why is it so important to keep ancient bone samples as uncontaminated with organic material as possible?

b. How can studying Neanderthal and Denisovan DNA help us understand ourselves?

Answer 1

1. Bone is composed of bioapatite, collagen and osteocalcin. The persistence of biomolecules in bone is unsual. In order to make these three components survive longer than their life, physical restriction to conformational flexibility and absorption must be imposed. The mineralization of bone makes it stable.

If the bone is preserved in chemical dissolution, then its protein gets exposed and it is at high risk of microbial attack. Hence, ancient bone samples must be kept as uncontaminated with organic material as possible.

2. Nearly 20 % of the Neanderthal DNA survived in modern humans and it is expressed in the skin, hair and several inherited diseases in present time. One example of this is the Vindija genome which has explained the cause of bone arthritis in modern humans. Neanderthal DNA also affects our psychological and neurological traits such as depression, smoking, feeling lonely, insomnia etc. Thus, it can be said that studying Neanderthal and Denisovan DNA has helped us understand ourselves