by Mallika Venkatramani
Imagine thundering footsteps at the dead of night; a beastly troupe making its way through salt marshes and ravines. They’ve hunted several bison and are making their way to the forest clearing to light a fire and make a meal. Wild and hungry, their knobbly fingers coated in grime, the beasts tear into their supper. Before you know it, 40,000 years pass and the forests and ravines are replaced with skyscrapers and houses. The only memory of these beasts that once roamed the earth is in science fiction and literature, which has named them ‘Neanderthals’.
No one really knows how exactly the Neanderthals lived. Perhaps they weren’t beasts at all, with humongous clubs and war-cries, as we see in sci-fi movies. Perhaps they lived just like us, talking, eating and breathing. No one can say for sure, although two things are clear. One is that they had a broader physique and larger brains than modern humans, as proven by extensive DNA analysis. The second is that they disappeared from the face of the earth 40,000 years ago, considering that no Neanderthal bone samples have been found that date less than 40,000 years in age.
Neanderthals weren’t the only hominin to exist at this time. The anatomically modern human (AMH) appeared around 45,000 years ago and co-existed with Neanderthals for a significant 5,000 years. The AMH, as their name suggests, are the closest genetic and morphologic match to the humans of the modern era.
So, what happened to the Neanderthals 40,000 years ago and why did they disappear? Some say a volcanic eruption ended them, while others argue that a war against the AMH wiped them out. A third theory suggests that the Neanderthals bred with the other hominins at that time and eventually became one with them, resulting in the humans of today.
The Volcano Theory
40,000 years ago, the Archiflegreo volcano (20km west of Mt. Vesuvius, Italy) erupted. Named the Campanian Ignimbrite, it remains one of the most significant eruptions in the history of natural disasters in Europe. A study by the Geological Society of America suggests that there was a severe drop in temperature (around 9˚C) towards the far east of the volcano and a less devastating drop of around 2-4˚C in the western regions of Europe, where most of the Neanderthal population is believed to have lived.
Unfortunately, the AMH were more capable of surviving this temperature change so outcompeted the Neanderthals, leading to their decimation. But could this change in temperature have disrupted day-to-day life so badly that an entire species got wiped out? The more compelling clue to this puzzle is that at the time of the eruption, the Neanderthal population was already decreasing, and the volcanic eruption might have just been the last straw to break the camel’s back!
The War Theory
So, the Neanderthal population was already sporadic before the volcanic eruption. What could have happened there? In the late 1950s, an excavation at Shanidar Cave in modern-day Iraq revealed peculiar things. Since then, 10 Neanderthal skeletons have been unearthed from there, with several of them showing severe injuries, ranging from rib fractures to massive blows on the face. The AMH of Western Asia were around at the time that the individuals died. As archaeological evidence suggests, the AMH had already developed weapons such as projectiles.
Leading on, a study at Duke University showed that Shanidar 3 (one of the Neanderthals unearthed from the cave) had a ribcage injury most likely caused by a low-kinetic energy projectile. Joining the dots suggests that there could have been a war between the two species (or a one-sided ambush)? Perhaps the advancement of the AMH served as an advantage that robbed the world of Neanderthals? This is a very plausible explanation, but if it was really a mass mutilation, you would expect evidence of more Neanderthal skeletons.
The Sex Theory
Advancements in genome sequencing presents a whole new argument…one where the Neanderthals didn’t disappear at all! Excitingly, this theory suggests that they’re still among us, a part of us. Cultural and physical advancements of the AMH had proven as a selective advantage that the Neanderthals couldn’t keep up with, so while the AMH numbers grew, the Neanderthal community declined. The logical solution then would have been to merge Neanderthals with the AMH. Today, many of us carry a minimal percentage of Neanderthal DNA. European and Asian populations carry 1-2% Neanderthal DNA, while African populations carry close to zero, because Neanderthals only appeared in Eurasia after their evolutionary ancestors left Africa.
Just to make matters more complicated, I’d like to introduce another hominin species – the Denisovans. They co-existed with the Neanderthals before the AMH even appeared. Denisovan DNA has been seen in today’s Southeast Asian and Melanesian populations. Parallelly, a 50,000 year old girl’s skeleton found in Russia showed that the girl had roughly equal Denisovan and Neanderthal parentage.
What this means is that whether our ancestors made war or didn’t, they definitely made love.
Before the sci-fi addicts among you go around thinking that you might be a ghostly relic of the rudimentary humans that once roamed the earth half-clad with buffalo skin wielding clubs, be assured that the Neanderthals (and Denisovans) might have done us some good. The Neanderthal and Denisovan DNA that many of us carry encode ancient genes that boost the immune system. That being said, carrying ancient hominin DNA does not influence us significantly in the grand scheme of things and the amount of DNA we share with these ancient hominins has little effect on selectively advantageous traits like strength or intelligence.
There are almost definitely more mysteries of the hominins waiting to be discovered and more things that will re-tangle the knots we untied, but for now, at least we can rest easy, knowing the Neanderthals fate.