Deep Time · Side by side

Two chapters, the same questions asked of both

Put two Deep Time chapters next to each other — their evidence base, the dating methods behind them, the live debates, and the questions still open.

Archaeological400,000 – 40,000 years ago

Neanderthals

Burial, pigment, and the genomic evidence for interbreeding with modern humans.

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Open Debate300,000 – 30,000 years ago

Denisovans

A population defined largely by DNA — and what a finger bone can and cannot tell us.

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The evidence base

Skeletons, Mousterian tool assemblages, burials, pigment and shell use, and sequenced ancient genomes.

A handful of physical remains and, unusually, far more genetic than skeletal evidence — including DNA recovered from cave sediment.

How we know
MethodWhat it constrains
Ancient DNA sequencingBone and tooth powder, and sediment DNA from cave floorsEstablishes population relationships and admixture. Contamination control is the whole ballgame.
Radiocarbon with ultrafiltrationCollagen from bone near the limit of the methodImproved pretreatment pushed many 'late' dates older, revising overlap estimates with modern humans.
Uranium–thorium dating of carbonate crustsFlowstone over cave art and structuresGives a minimum age for what lies beneath the crust, not the act itself.
MethodWhat it constrains
PalaeogenomicsA finger bone, teeth, and sediment-extracted DNAIdentifies a distinct population and its admixture. It cannot reconstruct anatomy.
PalaeoproteomicsCollagen peptide sequences from fragmentary boneAssigns fragments to a lineage where DNA has degraded. Resolution is coarser than genomics.
Population genetic modellingModern genome panelsEstimates admixture timing and proportion within an assumed demographic model.
Where specialists disagree
  • How much symbolic behaviour is securely Neanderthal?

    Several claimed cases turn on whether the dated crust really postdates the mark.

  • Why did they disappear as a distinct population?

    Competition, climate, demography and absorption by admixture are all on the table.

  • Which Asian fossils are Denisovan?

    Several candidate crania are argued for; assignment without molecular data stays provisional.

  • How many distinct Denisovan populations were there?

    Genomic signals suggest deep internal structure rather than one uniform group.

Still open
  • How large were their populations, and how fragmented?
  • How much of the assimilation happened where and when?
  • What did their language capacity actually look like?
  • What was their full geographic range?
  • Which archaeological assemblages did they make?
  • How did high-altitude adaptation pass into modern Tibetan populations?