Evolution, for the better or worse, is happening as we speak, not just through the conventional inheritance of genes from direct ancestors but even through genes acquired from other organisms by a process called horizontal gene transfer (HGT).
Such lateral means of evolution have been routinely proved in lower level organisms such as bacteria. Even sea slugs adapted to survive with only sunlight by acquiring functional nuclear genes from an algae and started to produce chloroplast proteins and synthesize chlorophyll.
In vertebrates though, this process of HGT has not widely studied due to unavailability of large data bank in earlier times. Recent work by researchers from University of Cambridge have shown that such lateral movement is widely seen even in higher order animals such as primates through genome-wide phylogenetic comparisons of high quality genomes. Tens or even hundreds of genes considered ‘foreign’ to the native genome have been acquired through HGT and have strong associations to metabolism and to immune reponses.
Different organisms have varying propensities to HGT, humans and primates gain fewer such genes since their common ancestor, with possible duplication of one HGT event and further diversification in the native genome. The report reclaimed or confirmed previously reported 17 genes as ‘foreign’ to humans with an additional 128 ‘foreign’ genes in the human genome.
Thus, horizontal gene transfer is possible in both vertebrates and invertebrates and is not just ancient but very much ongoing in our present day. What was originally believed to be inherited from our ancestors may very well be acquired from other organisms in an earnest bid to adapt and survive.
The original publication can be accessed here.