Biology Now, 2e

314 ■ CHAPTER 17 Animals and Human Evolution

BIODIVERSITY

4 percent. Most of us have a little Neanderthal

in us. But whether that nuclear DNA is the result

of thousands of sexual encounters between

humans and Neanderthals or a few one-night

stands remains unknown (Figure 17.12). When

Pääbo published his work in 2010, he and others

admitted it was possible that the shared DNA

wasn’t necessarily a product of interbreeding.

It could have been a remnant of DNA from a

common shared ancestor.

Pääbo spent 4 years sequencing the 1.5 billion

base pairs in the Neanderthal genome, using

DNA extracted from the femur bones of three

38,000-year-old females. Then he compared that

long, composite genome sequence to the genomes

of five living humans from China, France, Papua

New Guinea, southern Africa, and western Africa.

According to the results, all modern ethnic

groups, other than Africans, carry traces of Nean-

derthal DNA in their genomes—between 1 and

Figure 17.12

Nuclear-DNA inheritance

By sequencing the bases of nuclear DNA, scientists can determine how related an individual is to its

ancestors, both male and female (see Chapter 11). Mitochondrial-DNA sequencing can determine only

how related an individual is to the female ancestors on its mother’s side.

Q1: If a human-Neanderthal hybrid was born to a human mother and a Neanderthal father, could

you tell by whole-genome DNA sequencing that it was a hybrid?

Q2: If a human-Neanderthal hybrid was born to a Neanderthal mother and a human father, could

you tell by whole-genome DNA sequencing that it was a hybrid?

Q3: Under what circumstances are scientists able to do whole-genome sequencing, and when

are they restricted to mitochondrial-DNA sequencing?

Nuclear DNA is inherited

from all ancestors.

Mitochondrial DNA is inherited

from a single lineage.