Bringing Extinct Species Back to Life | Dr. Beth Shapiro

Shapiro spends several minutes explaining that species concepts are human inventions to facilitate communication. She uses examples: American bison called buffalo but not related to African/Asian buffalo; biological species concept (interbreeding) vs genetic species concept (sequence similarity). She emphasizes that the same animal can be different species depending on the concept used. This is foundational to understanding de-extinction: the goal is not to recreate a genetically identical individual but to engineer traits that make an animal capable of filling an extinct ecological niche.

Shapiro explains that before Neanderthal genome, we compared humans vs chimps; now we can compare to Neanderthal. The 5% of Neanderthal genome not found in any living human is where the human version was essential for survival. This is where we look for what made us human. She also discusses admixture events: Neanderthal and Denisovan interbred with humans; polar bear/brown bear hybridization example shows that hybrid bears only survive as brown bears, not polar bears due to adaptation.

Shapiro explains the four criteria: technical (DNA availability), ethical (should we?), ecological (niche still open?), social (public support). She gives example of mammoth: cold Arctic preservation; dodo from museum; dodo genome from bird that went to Europe. She also discusses that de-extinction is not about recreating exact genome but engineering traits that make animal capable of living in today's habitats. She uses direwolf example: 20 edits from fossil genomes, engineered into greywolf genome to recreate direwolf traits.

Shapiro explains that they sequenced genomes from fossil direwolves, learned genetic changes for size, robustness, light coat. They engineered those into greywolf genome. For coat color, they had to ensure safety: they didn't use exact direwolf variants because they could cause blindness/deafness in greywolf background. Instead, they used edits known safe from light-colored domestic dogs and greywolves. This is the approach for all projects: careful, staged, with animal welfare.

Shapiro explains the story: black-footed ferrets nearly extinct due to plague from prairie dogs. Captive breeding from Matiti Wyoming population. Low genetic diversity. They cloned Elizabeth Anne from 40-year-old frozen tissue, but she was infertile. Another clone reproduced. Also, they are working on editing ferrets to be resistant to plague, using synthetic biology. This is a direct application of de-extinction tools to save living species.

Shapiro discusses gene drives: they can be made to last only a fixed number of generations, and natural selection works against them. She gives example of cheatgrass in California, which is invasive and causes fires. She suggests that using a gene drive to reduce cheatgrass for a few generations could allow native grasses to recover. She emphasizes that doing nothing is also a decision, and we must consider risks vs benefits.

Shapiro discusses that we already do genetic selection by choosing mates. Height is heritable and has been selected in Northern Europe via migration. She argues that what offends us about embryo selection is that it removes the child's freedom to choose their own path. She also mentions that a pandemic could push us over the edge to accept gene editing for survival. She uses the example of baby KJ cured of urea cycle deficiency using CRISPR base editing, which was celebrated, not condemned.