On the trail of the Denisovans
Multiple commenters use recent research on Denisovans and other archaic humans to reflect on how many hominin lineages once coexisted and how all but Homo sapiens have vanished, raising questions about our own long‑term survival. They debate how vulnerable modern humans really are to threats such as climate change, nuclear war, pandemics, and volcanism, contrasting our huge global population and technology with the track record of past extinctions. Along the way, they touch on what sparse fossils and ancient DNA can reliably tell us about Denisovan behavior, interbreeding with Neanderthals and modern humans, and how much of their genetic legacy persists in present-day populations.
Human extinction risk
- Several comments note that many hominin species coexisted in the past and all but one went extinct, implying modern humans are not exempt.
- Others argue extinction is now very hard: 8+ billion people across all continents make total eradication unlikely; climate change and even global nuclear war are seen as civilization‑threatening but not species‑ending.
- Suggested true extinction drivers: cosmic events, engineered or novel pathogens, extreme volcanism, or unknown future technologies.
- Some see humanity as “our own great filter” via climate change, overpopulation, war, ecological collapse, and hubris; others stress historical progress and underestimate near‑term extinction risk.
- Debate over whether we are in a temporary “Wile E. Coyote” phase where growth hides underlying fragility.
Climate change, heat, and technology
- Disagreement over whether climate change could directly kill most humans via heat stress or food‑system collapse.
- One side cites physiological limits of sweating at high temperature/humidity and warming trends; another counters with personal adaptation, technological growth, and likely geoengineering.
- Air conditioning is proposed as a solution; critics point out thermodynamic limits, waste heat, energy requirements, and impossibility of cooling fields, oceans, and outdoor labor at scale.
- Concern is expressed about scaring younger generations into fatalism vs motivating realistic action.
Other human species and our ancestry
- Discussion of Neanderthals, Denisovans, and other hominins: small ancient populations, likely outcompeted and affected by climate shifts.
- Some emphasize that their genes persist in modern humans, especially in Asian populations, so they are “not entirely extinct.”
- Debate over Neanderthal cognition and language: similar brain size but different organization; possible smaller, more fragmented societies vs larger human tribes.
- Taxonomy is seen as a simplification; suggestions that Neanderthals might be reclassified closer to Homo sapiens.
Denisovan evidence and ancient DNA
- Skepticism that a handful of Denisovan bones justifies detailed behavioral claims or statements about communication with modern humans.
- Questions about how skull fragments are identified as distinct and whether DNA evidence is robust.
- Multiple replies distinguish consumer genotyping from full ancient‑DNA sequencing: different technology, depth, and lab rigor.
- Convergent evolution is raised as an alternative to introgressed high‑altitude genes; others argue identical DNA sequences plus context strongly favor introgression.
- Possibility that some Asian “Homo erectus” fossils are actually Denisovans, and speculation about their main geographic range and the chance of frozen finds.
Long‑term human traces
- Speculation about which human works might persist for millennia: dams, seed vaults, open‑pit mines, terracing.
- Counterpoint that most large structures and terraces are geologically unstable and would erode, flood, or silt up without maintenance.