The Reason Beards Cover The Jawbone

Jawbones can provide a link between Neanderthals and humans because some discovered jawbones show a mix of Neanderthal and modern human physical traits and genetic evidence of interbreeding, such as the 2002 Romanian jawbone that displayed characteristics of both species. Analysis of such fossils reveals genetic evidence of a close, recent Neanderthal ancestor in early modern humans, confirming that modern humans and Neanderthals interbred in Europe. 

Evidence from Jawbones

• Oase Cave Jawbone: 

  A jawbone discovered in Romania's Peștera cu Oase (Oase Cave) is a significant example. DNA analysis of this ~40,000-year-old fossil revealed that the individual had a recent Neanderthal ancestor, only a few generations back. The jawbone itself showed a blend of modern human and Neanderthal characteristics. 
• Morphological Characteristics: 

  The physical features of some jawbones can show intermediate traits between classic Neanderthals (who had a receding lower jaw) and modern humans (with a projecting jaw and chin). 

Genetic Confirmation

• The discovery of these mixed-trait jawbones provided crucial genetic confirmation that modern humans and Neanderthals interbred not just in the Middle East but also in Europe. 
• Researchers found that the Oase individual had large segments of Neanderthal DNA, indicating a close ancestral link. 

Conclusion

These jawbone fossils serve as tangible proof of interbreeding between early modern humans and Neanderthals, highlighting the complex evolutionary relationship and shared ancestry between the two groups.