In 2,001 Celera Genomics and the International Human Genome Sequencing Consortium published their initial drafts of the human genome, which revolutionized the field of genomics. While these drafts and the updates that followed effectively covered the euchromatic fraction of the genome, the heterochromatin and many other complex regions were left unfinished or erroneous. Addressing this remaining 8% of the genome, the Telomere-to-Telomere (T2T) Consortium has finished the first truly complete 3.055 billion base pair (bp) sequence of a human genome, representing the largest improvement to the human reference genome since its initial release. The new T2T-CHM13 reference includes gapless assemblies for all 22 autosomes plus Chromosome X, corrects numerous errors, and introduces nearly 200 million bp of novel sequence containing 2,226 paralogous gene copies, 115 of which are predicted to be protein coding. The newly completed regions include all centromeric satellite arrays and the short arms of all five acrocentric chromosomes, unlocking these complex regions of the genome to variational and functional studies for the first time.

The latest major update to the human reference genome was released by the Genome Reference Consortium (GRC) in2013and most recently patched in2019(GRCh38.p13). This assembly traces its origin to the publicly funded Human Genome Project and has been continually improved over the past two decades. Unlike the competing Celera assembly , and most modern genome projects that are also based on shotgun sequence assembly , the GRC human reference assembly is primarily based on Sanger sequencing data derived from bacterial artificial chromosome (BAC) clones that were ordered and oriented along the genome via radiation hybrid, genetic linkage, and fingerprint maps. This laborious approach resulted in what remains one of the most continuous and accurate reference genomes today. However, reliance on these technologies limited the assembly to only the euchromatic regions of the genome that could be reliably cloned into BACs, mapped, and assembled.

Are there vertebrates occupying the planet today whose lifespans extend back to before the founding of the United States? Based on recent research, it seems very likely — and they exist in the form of sharks whose fermented meat are used in a very distinctive Icelandic dish. Scientists have found evidence that Greenland sharks live for hundreds of years — and that there are some whose lifespans extend to 400 or even 500 years.

For some scientists, the lengthy lifespans of certain creatures can also have an impact on research into making humans live longer. That’s true for the immortal jellyfish, and it also applies to the Greenland shark. A recent article by Jonathan Moens at Atlas Obscura explores what scientists have learned from their studies of the long-lived sharks — and what it might mean for humanity.

Greenland sharks’ longevity could be chalked up to genetic or lifestyle factors, or some combination of the two. The University of Manchester’s Holly Shiels suggested that, as Moens writes, “Greenland sharks may have a uniquely sophisticated system to repair damaged DNA.” Other scientists point to the sharks’ habitat — cold Arctic waters — and their ability to live for a long period of time on a relatively small amount of food as signs of a very efficient metabolism.