As per the study published in the journal Genome Biology and Evolution in February 2020, scientists decoded the genome of one of the last mammoths from Wrangel Island, Russia. The report states that world’s last woolly mammoths suffered from serious genetic defects due to inbreeding that may have hampered sense of smell and male fertility.
For the study, scientists actually raised the mammoths’ genes from the dead, and placed them in elephant embryo cells in the lab to see how well they functioned.
Key Takeaways
Some of the key takeaways from the study are as follows:
- The last woolly mammoths quietly died on their final bastion, the isolated Wrangel Island, north of Russia in the frozen Arctic, four thousand years ago. Their demise was sudden and strange. Some new evidences suggest that the mammoths themselves were partial agents of their own demise.
- The mammoths, Mammuthus primigenius, were afflicted by genetic diseases, possibly due to a lack of genetic diversity. With decline in their numbers, the pool of available mates grew ever smaller leading to increase in detrimental genetic mutations and unhealthy herd.
iii. The genes were sad, stumbling, and broken that could have seriously impaired important functions, such as male fertility, and the mammoths’ sense of smell.
- Probably, the last mammoths were an unhealthy population. So, it is a cautionary tale for living species, which are threatened with extinction. If they stay small, they too may accumulate deleterious mutations that can contribute to their extinction.
- The male animals also had higher rates of male infertility and diabetes as well as neurological defects, which would not have been the only factor contributing to the end of the woolly mammoth.
- Their deaths began 11,700 years ago, towards the end of the last ice age. As the world warmed and humans spread, mammoths petered out. Just under 10,000 years ago, the species was extinct from its extensive mainland habitat across Eurasia and North America.
vii. The drastic decline of numbers decreased genetic diversity, which meant that the animals were inbreeding to a higher degree, and less capable of purging bad mutations.
Last year, isotope analysis of the bones and teeth of the animals revealed dramatic changes in the mammoths’ diet that point to drastic environmental changes. Earlier also, scientists had conducted complete genome sequencing on Wrangel Island woolly mammoths. The results were published in 2017, which stated that accumulation of detrimental mutations … were consistent with genomic meltdown. The present research builds on the 2017 paper, and the results are very complementary. The 2017 study predicted that Wrangel Island mammoths were accumulating damaging mutations. The scientists also compared it to the genomes of two other mammoths—one from 44,800 years ago, and another from 20,000 years ago, when the populations were large and hale. The scientists were able to identify mutations related to defects in sperm morphology; neurological development; insulin signalling; and olfactory receptors from these comparisons.
Thereafter, these mutated genes were raised from the dead. They synthesised and cloned the genes, then placed them in gene-edited elephant embryos in a petri dish to observe how proteins expressed by the genes interacted with other genes and molecules. The study also helped scientists to know how the genes responsible for our ability to detect scents work.
The scientists resurrected the mammoth version, made cells in culture produce the mammoth gene, and then tested to know whether the protein functions normally in cells. If it does not, they can infer that it probably, Wrangel Island mammoths were unable to smell the flowers that they ate.