Differences in the limits and range of aerobic activity levels between endotherms and ectotherms remain poorly understood, though such differences help explain basic differences in species' lifestyles ...

The sympathetic nervous system, which enables the fight-or-flight response, was thought to be present only in jawed vertebrates. Analysis of a jawless vertebrate suggests that this system might be a ...

Scientists once thought that humans must have two million genes to account for all our complexity. But since sequencing the human genome, we've learned humans only have about 19,000 to 25,000 genes - ...