Complex sentence: However, in 2015, scientists from the US and UK mapped the whale's genome and identified two alleles that differed from those in minke whales and could be responsible for the difference in their longevity.
Split into simpler sentences: However, in 2015, scientists from the US and UK were able to successfully map the whale's genome. Through comparative analysis, two alleles that differed from those in minke whales were identified which could be responsible for the difference in their longevity.