Generation times and the molecular clock

The life history traits of humans are thought to very unique and have evolved very recently in their evolutionary history. According to the “Generation time effect hypothesis”, this slow life history of humans that resulted in a longer generation times, have also brought about slow rate of molecular evolution compared to our closest relatives due to accumulation of fewer substitutions. A study by Elango et al, which looked at single nucleotide substitution on a large-scale sequence comparisions, indicates that there is indeed a slow molecular evolution in humans compared to other Hominoids. However, the slight differences observed in comparisons with Pan indicate that this is a more recent development. The study also suggested that humans and chimpanzees have slower molecular clocks compared to gorillas and orangutans.