Smelling One Trillion Smells

A study recently estimated that human beings can detect 1 trillion different smells. At least half of those smells apparently are found somewhere in the average high school boys’ locker room. (Just kidding!)

In the study, the researchers mixed different “odorant” molecules in combinations, provided participants with three vials of scents, and asked them to identify the outlier in the group. The participants were, on average, adept at distinguishing between the different smells. The researchers then multiplied the different combinations to come up with their estimate of one trillion. Believe it or not, one of the researchers is convinced that the estimate of one trillion — 1,000,000,000,000 — is almost certainly too low.

One trillion is a lot of smells, but the conclusion is plausible from an evolutionary standpoint. The researchers believe the odor-detection capabilities are directly related to the hunter-gatherer history of homo sapiens, because our distant ancestors relied on their sense of smell as a key component in their ability to track prey, sense enemies, determine whether food remained edible and water was potable, and otherwise detect danger. If you couldn’t smell a silently approaching saber-tooth tiger and skedaddle, or make a judgment that the fly-blown piece of woolly mammoth haunch that you were planning on eating for lunch remained edible, you weren’t likely to survive to reproduce.

The recent study joins other studies that indicate that human senses are remarkably discriminating. Along with the ability to use our olfactory capabilities to detect one trillion smells, other studies conclude that the human eye can distinguish between several million shades of color, and the human ear can discern 340,000 different sounds. Talk about sensory overload!

Farmers On The Move

How did humans stop wandering and start farming?  It’s a crucial question, because farming allowed our ancestors to move beyond itinerant lifestyles into more permanent cultures.  When farming was adopted, and people saw the benefits of having food at the ready, early humans put down roots (pun intended), established long-term structures, and began to defend their territory and protect their possessions.  Civilization as we know it was the ultimate result.

There are two competing theories.  One is that early farmers migrated from their home area and brought their seeds, tools, and farming concepts with them.  The other posits that hunter-gatherers saw the benefits of farming and decided to adopt the farming lifestyle.  The latter theory seems a bit far-fetched, because it’s hard to imagine hardy hunter-gatherers appreciating the benefits of farming and radically changing their transient ways.

Now DNA studies have lent support to the former theory and indicate that farming was spread through Europe by migrants.  The study found that a Stone Age farmer was genetically distinct from hunter-gatherers of that era, and suggests that farming began in the area now known as Turkey and spread north and west, as farmers looked for tillable acreage where their crops could thrive.  The study also suggests that modern Europeans have more genes of the early farmers than they do of the hunter-gatherers.

In short, the farmers won the Darwinian contest.  Their lifestyle might have been boring compared to that of the hardy hunter-gatherers, but with their steady diets, domesticated animals, and focus on building for a better harvest next year, they were more likely to survive and pass down their genes.