Is the rate of human evolution increasing with population growth?

Larger populations create more chances for genetic mutations to occur, and this means more variations for natural selection to either favour or weed out. But in big populations, it takes longer for chances to spread. The fastest rate of evolution occurs when a population is split into isolated subgroups that can’t interbreed due to geographic or cultural barriers. Travel and communication have broken down many barriers, so our genes get blended together instead of splitting into subspecies. A 2007 study found that we are evolving about 100 times faster than at any other period in our history. But ‘modern’ for an evolutionary biologist means the last 5,000 years. It’s too soon to tell how our evolution has been affected by the population explosion of the last few centuries.

HOW DO GRAVITONS ESCAPE FROM A BLACK HOLE?

In Einstein’s theory of General Relativity, the force of gravity around a black hole is described solely by the warping or curvature of ‘space-time’. However, many scientists believe we can also describe gravity, just like the other forces of nature, as the exchange of ‘virtual’ particles – in the same way that particles of light, photons, carry the electromagnetic force. Unfortunately there is, as yet, no such quantum theory of gravity that would describe how it works at this level, although we have some clues as to what it might look like. But crucially, these ‘virtual’ gravitational particles (called ‘gravitons’) aren’t bound by the normal rules of physics. They can pretty much do what they like, including travelling faster than light, as long as they do it before we notice them! Consequently, a black hole’s event horizon presents no barrier to gravitons and hence their communication with the outside Universe.