Artifacts reveal humans arrived in Australia 20,000 years earlier and lived alongside giant kangaroos and tortoises
  • New research suggests humans arrived in Australia 65,000 years ago.
  • This would mean they lived alongside the continent's unique megafauna.
  • Some experts have argued that humans may have caused their extinction.
  • Researchers involved in study argues new evidence suggests this is not the case.
  • Not everyone is convinced however, arguing that arriving on the continent early gave them more chance to wipe out the megafauna.