How Do We Really Seek Partners?

When times are tough, we change plans, just like other creatures.

Post published by Glenn Geher Ph.D. on Aug 03, 2015 in Darwin's Subterranean World

 From the evolutionist's perspective, humans are really just another part of nature. Since Darwin’s time and prior, naturalists have documented patterns of phenomena and laws of nature (such as natural selection) that cut across species and classes of organisms.
In the study of human mating strategies and behaviors (see Geher & Kaufman, 2013 (link is external)), several scholars have documented a plurality of strategies within each of the sexes (see Gangestand & Simpson, 2000). That is, more than one mating strategy exists in the toolbox of all adult humans. For instance, under highly stressful ecological conditions in which adults are highly at risk for violence and early mortality, both males and females are relatively likely to utilize short-term mating strategies (see Figueredo et al., 2005)—whereas under highly stable and resource-rich conditions, long-term mating strategies tend to be favored. Several other ecological factors, such as prevailing sex ratios, have been shown to influence the nature of human mating strategies (see Geher & Kaufman, 2013 (link is external)). The reproductive strategy that an organism implements is likely to be carefully calibrated to ecological conditions. Evolutionary forces favor such ecological sensitivity.
What You Can Learn From Your Garden
Each summer I grow a vegetable garden. As an evolutionist, I’ve realized that the primary job in cultivating the garden is to foster survival and markers of reproductive success of the many plants I’ve worked with for months. As someone who constantly thinks about connections between the natural world and what it means to be human, I recently got to thinking about the reproductive strategies of garlic (which sometimes succeeds in our family garden).
You see, like humans, garlic plants in the wild demonstrate a plurality of reproductive strategies. This is why wild garlic plants include both bulbs and flowers (see Ronsheim 2010; Ronsheim & Bever, 2000). Under highly stable environmental conditions—when things are good, so to speak—wild garlic plants reproduce asexually via their bulbs. Asexual reproduction essentially means that they create clones of themselves. If the ecology signals security and stability—if things are good and pathogens are few and far between—then why not just repeat what’s working already? Don't mess with a good thing seems to be a part of the evolved strategy of wild garlic.
Sometimes (as in the lives of humans) bad things happen: Pathogens might appear in disproportionately high numbers—making survival and reproduction less likely for our poor wild garlic protagonists. What do they do? Under stressful, pathogen-laden conditions, wild garlic plants are more likely to reproduce sexually via flowers or seeds. These things have an arsenal of tools that are totally ready to take on whatever challenges the environment presents—why would sexual reproduction be more optimal under high-stress conditions? Sexual reproduction produces offspring that have much genetic diversity compared with clones. So if the current conditions are stressing the plants out, the strategy seems to be “let’s create something a little different in hopes that these new, genetically diverse offspring can (by random chance) fare better under these austere conditions.”
Wild garlic plants clearly demonstrate a plurality of reproductive strategies—just like humans.
On Hominids, Sexual Strategies, and Garlic, Revisited
Garlic plants provide a great evolutionary model for understanding human mating strategies. Their reproductive systems are complex and are ecologically sensitive. They implement different strategies under highly stable conditions compared with conditions that are unpredictable and threatening. Humans also implement different reproductive strategies when conditions are highly stable vs. when conditions are highly unpredictable (see Figueredo et al., 2005):

• When resources are rich and lifespans are expected to be long, humans are more likely to show proclivities toward monogamy, as long-term strategies are effective at producing high-quality offspring under such conditions.
• Under highly unstable conditions, humans are more likely to utilize short-term, fast mating strategies. Such strategies are relatively adaptive when futures are uncertain for any individual offspring.

The conditional nature of human mating strategies is a lot like the conditional nature of garlic mating strategies, when you think about it. The evolutionary perspective provides a beautiful foundation for understanding what it means to be human. It puts us on the same footing as wild garlic, cucumber plants, pumpkins, osprey, olive baboons, great blue herons, white pine trees, and the rest of the entirety of life.