Science and Creationism 19. Populations © Colin Frayn,

© Colin Frayn, Exponential Growth No population can continue growing forever Populations grow exponentially –The rate of growth is proportional to the current population size –So the growth rate keeps increasing! This is a very simplistic model –Other effects stop populations growing Lack of food Disease Natural disasters Warfare We can’t ‘rewind’ population growth to see when civilisation began –Because this exponential assumption doesn’t hold

© Colin Frayn, Minimum Stable Population How many individuals do you require for a ‘stable’ population? –Small chance of extinction due to Predation Famine Disease Genetic disorders caused by inbreeding Genetic bottlenecks –With only two (or even 7) ancestors, species would have suffered from extreme levels of inbreeding –This massively increases the chance of genetic diseases –Also, it would be measurable today What did carnivores eat on (and off) the Ark? –They can’t have eaten other animals until the numbers recovered!

© Colin Frayn, Tracing Mitochondrial DNA How many generations of humans have there been? –The Bible says ‘less than 300’ We can test genetic relatedness ‘Mitochondrial DNA’ –This is found in components of all our body cells –It is passed only down the female line, in eggs There is no genetic mixing with paternal genes –It can be traced back to a common ancestor –Roughly 140,000 years ago –So we know humanity is at least this old That’s 7,000 generations A Eukaryotic cell. This is what human cells look like.

© Colin Frayn, Population Growth Hovind claims that increasing human population is a good thing Increased population leads to: –More pollution Global warming –More rapid depletion of vital resources –Faster spread of diseases –More destruction of natural habitat Greater rate of extinctions –More destruction of scenery –More rapid depletion of fish and seafood