Love is in the air for humans, critters
As spring in Colorado slowly approaches, animals of all kinds are preparing to meet, mingle and mate. These days, the sun is shining a bit longer, prompting the release of sex pheromones out onto the warming winds. These pheromones, or chemical signals, can travel in the air for miles and trigger a social response in members of the same species. Sex pheromones specifically focus on indicating females for breeding, attracting the opposite sex, and conveying information on an individual’s age, gender and even genotype, vital information to know when deciding on the right mate for the reproduction of healthy offspring.
All animals from insects to mammals release a variety of pheromones through specialized glands, skin, urine, feces and their breath. Yes, even human beings secrete these chemical signals from our sweat glands. Our brains pick up on these floating pheromones subconsciously and our bodies respond accordingly. This was demonstrated by Swiss zoologist, Claus Wedekind, when he conducted the famous “sweaty t-shirt experiment” in 1995, bringing new light to the understanding of human pheromones. Claus selected 44 men with differing MHC gene types and instructed them to wear a clean T-shirt for two nights before returning them. Next, 49 women volunteers were invited to sniff each shirt and rate their odors by intensity, pleasantness and (most importantly) sexiness. The results conveyed that the women generally preferred the odors of men whose MHC gene types were most different from their own. This study suggests that evolution has provided humans with the faculties necessary to process genetic information through pheromones, which may influence our mate choice. All this even before the first date!
Season of New Growth
It’s no coincidence either that we of the human species feel the love bug bite around this time of year, celebrating Valentine’s Day by cuddling up next to our darlings and reminding them how much we care. Spring is the season of new growth and an ideal time of year for reproduction and raising young. Throughout evolutionary history, natural selection has favored late winter and early spring breeding in many species. This way, animals can bear and rear their new offspring throughout the remainder of spring and into summer, the seasons of plenty, without needing to worry about finding enough food, water and good shelter. This also ensures the offspring will grow up strong and healthy and be physically prepared for surviving the tough winter months ahead of them.
Benefits of Monogamy
Natural selection has also favored monogamous pairing in certain animals throughout evolutionary history, but the reasons are far from romantic. Monogamy is one mating system that refers to forming pair bonds that last an individual’s lifetime, (or at any one time), and has been found to be very advantageous for animals who bear vulnerable offspring that would benefit from the care of both parents. This is one reason why monogamy has been so highly valued in many human cultures, because fragile human infants take a long time to reach maturity. Monogamy can also benefit the mating pair in terms of protection, finding food and water sources, and building or maintaining shelters.
In Colorado, many animals follow a monogamous mating system. Black vultures are known to attack single vultures that get too friendly with their mate. Bald eagles will only seek out another mate in the event of death or impotency of the first and coyotes have been observed participating in social monogamy, meaning pairs will live, hunt and care for young together, but may not necessarily form sexually exclusive pair bonds. But just like most things in life, monogamy doesn’t work for everyone. Each creature must follow their individual nature for the good of their own kind, as successful reproduction of the species is the reason for the season.
May the love bug bite you too this sappy season!
Nicole Abrams is the Avon in-school and girls-in-science coordinator at Walking Mountains Science Center in Avon. She loves her responsibility of fostering a sense of place in the natural world for all her students.