Ancient Penguin Discoveries and Evolution
In a recent BBC News article, Ivan Noble discusses the possibility that ancient penguins may hold the key to unlocking the mysteries behind the complicated molecular clock of evolution. Although a seemingly unlikely animal to research, prehistoric penguin remains in the Antarctic often have been the basis for study, research, as well as debate in the modern science world. Because the prehistoric relatives of the cute and cuddly modern day birds have colonies that are “characterized by high densities and high mortality”, large deposits of the subfossil bones “have been serially preserved in the cold Antarctic environment” (Lambert & Ritchie), making the animals prime candidates for scientific research and testing. Massey University’s David Lambert along with his colleagues have recently unearthed the remains of two distinct types of ancient Adelie penguins living in the Antarctic (Noble), and his findings may prove vital to a better understanding of far more than simply an advancement in the penguin fossil record. By digging past Noble’s article and into the original study reported in Science Magazine, the actual significance of the Adelie Penguin study becomes clear.
The penguins’ remains are crucial in order to identify and to contrast individual differences between the two lineages throughout history. Not only have scientists compared the ancient DNA of the two types with each other, but also they have expanded their comparison to include living penguins as well. Out of the 96 radiocarbon-aged bones tested (the oldest fossil dating back nearly 8000 years ago), the scientists found “large numbers of mitochondrial haplotypes” (Lambert & Ritchie), some of which now appear to be missing from the test sample of the 380 modern-day relatives of the birds. The absence of these mutations in the modern DNA reveal a lot about the differences between the ancient penguins and their modern day counterparts. The distinctive mutations, which are thought to “occur at a steady rate” (Noble), can then be traced, tracked, and recorded in the fossil record.
Determining the age of the remains proved critical in the discovery. In this study, ancient penguin “guano” (an accumulation of dung) was radio-carbon dated to ensure accurate sequencing. Ages also were assigned to nucleotide sequences from bones, either because the “bones themselves were directly dated or strata from which they were isolated were dated” (Lambert & Ritchie). The radiocarbon ages of Adélie penguin bones demonstrate that both mitochondrial lineages were present at least 6082 years ago, and possibly as far back as 8000 years ago.
Surprisingly, it is not the fossils’ themselves, or even the fossils’ old age, that makes the discovery unique. The DNA samples from these bones, however, offer valuable insight into the same molecular clock that scientists use to investigate the evolutionary history of animals. Because the...