They found that animals with two of the same sex chromosomes — such as birds with two “Z” chromosomes — live nearly 18 per cent longer. Their research piggybacks on a pre-existing theory ...

Each human body cell contains 46 chromosomes. These can be arranged into 23 pairs. Each chromosome in a pair carries the same types of genes. The 23rd pair are the sex chromosomes: In females ...

Many bird species are monogamous. However, genetic studies have shown that the social partner is often not the genetic father of all offspring. Some studies found biased sex ratios: more males than ...

Some molecular complexes required for cellular respiration are composed of proteins, some of which are encoded by nuclear genes on the sex chromosome Z and others by mitochondrial genes.