When farming evolved it marked a huge step in human (pre)history. It forced us to settle down, developing a village into a city and - eventually - civilisation. But these benefits of farming took a while to appear. In fact, early farmers actually suffered a great deal. So why did our ancestors stick with it?
After all, farming is a lot more work than hunting and gathering. Increased proximity to animals puts you at a higher risk of disease. And only a few plants and animals were domesticated at first. As such the first farmers had a rather appalling, monotonous diet.
And yet farming still took off. After a few thousand years the benefits started to show, and farming spread around the world like wildfire. But why did they keep farming for those intervening thousands of years? What were the actual benefits of farming?
It was babies. Lots and lots of babies.
Farming evolved as a murderer
Nowadays farming is at the heart of everything that makes humanity great. It allows most of us to do something other than farming, freeing up all those man-hours for invention, innovation, and blogging. The latter being just as important, of course.
Yet the benefits of farming were initially dwarfed by the costs. Early farmers had to deal with:
- More rotten teeth as they were eating more dietary sugars
- Proximity to animals allowed diseases to spread from them. The most famous example being the ruddy plauge! That's all farming's fault.
- Since a small number of plants and animals were initially domesticated, diet breadth was lower. Early farmers just weren't getting their five a day.
- Arthritis and other joint problems induced by the repetitive motions associated with farming.
- Higher infant mortality
These are all problems the Agta know too well. They are a group of 10,000 indigenous people living on the Philippines. They're one of the smaller indigenous groups in that country, but scientifically they're invaluable. This is because there's a lot of variation in how they live. Some still live a (mostly) hunter-gatherer lifestyle. However, other groups have begun settling down and farming. These first farmers are encountering the same problems our ancestors did when they farming evolved 10,000 years ago.
As such, similar groups can be compared to see just how bad farming is. And sure enough, a recent survey of Agta groups confirmed that it is pretty terrible. The groups which were farming were also suffering as a result. More of their kids were dying, disease was spreading through their villages, and people just weren't living as long.
The secret benefit of farming
Farming seems like a rather horrible way to live, given those factors. Whilst things have improved, it had to stick around long enough to get good. Why did the early farmers keep going on such a harsh path?
Many different explanations have been proposed over the years. Some have argued that farming was more predictable. Others note that since you only need to farm for a brief period of the year that frees up time for fun and games and innovation. However, none of these explanations really have the evidence needed to support them.
For example, farming is actually a lot more risky than hunting and gathering because it's the dietary equivalent of putting all your eggs in one basket. If your crop fails then you're in serious trouble. As such it should come as no surprise that early farmers experienced massive population crashes as the risky nature of farming bit them in the behind.
However, the same research on the Agta which demonstrated so many of those bad consequences of farming also found a massive benefit: more babies.
It was certainly true that the groups which farmed had a whole host of extra problems. But despite this women were able to have more babies. Now, more babies died, and those which survived had all the aforementioned health problems. Yet the number of babies surviving was still larger than in foraging societies.
This seems to be because hunting and gathering requires a lot of walking about. That's a whole host of energy being spent not growing a kid or producing milk for kids you've finished growing. By transitioning to a sedentary, farming society that energy is freed up. It all goes straight into reproduction, allowing more babies to be born.
Farming evolved because it produces such a quantity of babies that the quality doesn't matter as much.
A million year old problem
When farming evolved it wasn't the first time fertility had influenced our ancestors diet choice. Dealing with the fact it takes a lot of energy to grow a baby in a belly has been a problem as long as - well - babies in bellies.
In fact, it may have been one of the factors that drove our ancestors to eat meat in the first place. Millions of years before we began domesticating animals, Homo erectus was hunting and eating them. Many argue that this was to use that protein-y goodness to fuel their growing brains. However, research has found relatively little link between brain and guts in other mammals, suggesting this sort of relationship might not be as significant as thought.
However, one other key benefit of eating a lot of meat is that all that protein can help mothers recover after giving birth. Carnivores can wean their young faster and recover quicker because of all the meat they're getting; benefits which would have surely helped early humans. And still continue to help us to this day.
Chimps also seem to recognise this benefit, with pregnant and new mothers eating more meat than average. Coincidentally, female chimps are also the ones who invented spears to aid with their hunting. Of course no link with pregnancy has been studied; so it might just be the case that lady chimps are naturally more blood thirsty.
Clearly, dealing with the costs of reproduction has been at the heart of our evolution for as long as we've been recognisably human. It drove our ancestors to start eating meat and, later, to start farming that meat too. I guess that shouldn't be too much of a surprise given evolution is all about passing on genes. So reproduction is going to be at the heart of any evolutionary change. Even why farming evolved.
Nevertheless, it's interesting to know trying to get more food for mum is the reason for all human civilisation.
tl;dr
Farming evolved because it increased the fertility of farmers. It also increased their mortality rate, but the rise in fertility was more than enough to offset this.
References
Page, A.E., Viguier, S., Dyble, M., Smith, D., Chaudhary, N., Salali, G.D., Thompson, J., Vinicius, L., Mace, R. and Migliano, A.B., 2016. Reproductive trade-offs in extant hunter-gatherers suggest adaptive mechanism for the Neolithic expansion. Proceedings of the National Academy of Sciences, 113(17), pp.4694-4699.
Psouni E, Janke A, & Garwicz M (2012). Impact of carnivory on human development and evolution revealed by a new unifying model of weaning in mammals. PloS one, 7 (4) PMID: 22536316
Shennan, S., Downey, S.S., Timpson, A., Edinborough, K., Colledge, S., Kerig, T., Manning, K. and Thomas, M.G., 2013. Regional population collapse followed initial agriculture booms in mid-Holocene Europe. Nature Communications, 4.
