In preparation for Valentine’s Day, humans across the world are investing in chocolates, flowers, lacy garments, and, for those who have read 50 Shades of Grey, perhaps a few additional supplies. For some of us, it’s the perfect excuse to stuff our faces with chocolate and sulk over singledom. In my case, I sat around craving chocolate and randomly announcing disturbing aspects of animal mating behavior to my resigned friends and family. In honor of this lovey-dovey holiday, I present a blog on how the epic battle to get laid has led to the development of some extremely peculiar methods of winning over a potential mate and competing with rivals.
The struggle is real, ladies and gents, and you’re not alone!
Animals have been evolving toxins for millions of years, perfecting the art of paralyzing prey, killing targets, and deterring predators. While poison is either ingested or inhaled, venom is toxin delivered directly into the target’s circulation by means of a bite, sting, or other rudely penetrative means. Even the more mild venoms from tiny insects are impressively efficient; a bee can create havoc in an animal hundreds of times its own mass (a 1/10 gram bee compared to a 70 kilogram human).
Despite the fact that some of us experience complete mental breakdowns the minute a venomous creature passes by, humans have been harvesting and utilizing animal venom for hundreds of years. The key to many of these toxins is their astonishing specificity; they bind to an exact spot on a specific protein in only certain types of cell to achieve an precise, and devastating, effect. This incredible feat is far beyond our own ability to engineer, and so we study these toxins, altering them for use in life-saving therapies and medicines. In order to celebrate these amazing chemicals (and because venomous animals are too cool to pass up), let’s see how some of the deadliest venoms work.
If you have a weak stomach, you may want to turn away now. Parasitism is unpleasant at the best of times, but occasionally it can get downright creepy. Some organisms have perfected the art of infection to the point of controlling the minds and behavior of their hosts. I’ve previously discussed Toxoplasma gondii, a behavior-altering parasite that has spread to infect over a third of the human population, but there are many other parasites that infect non-human hosts in more extreme ways. While the examples I have included in this post are not exhaustive by any means, they are some of the most bizarre and spine-chilling examples of parasites taking control.
Tardigrades: Animal Survivors
We’ve covered the nigh invulnerable bacteria Deinococcus radiodurans and near-indestructible prions, but what about animals? Generally, animals do not come to mind when we think of surviving in extreme environments; we’re a little too squishy to survive in vacuums, sub-Antarctic temperatures, or sans water. However, there are a few astonishing animals that have mastered survival skills that put the rest of us to shame, and even offer up a challenge to D. radiodurans. The animal phylum Tardigrada contains species of Tardigrades that can survive 10 years without water, subsist in temperatures from -196°C (-320°F) to 151°C (304°F), live in a vacuum or under six times the pressure of the deepest point in the ocean, shrug off 5,000 Gy of gamma radiation and 8,000 Gy of heavy ion radiation, and dodge the toxic effects of most environmental toxins. These astounding animals have been given very dignified and fearsome nicknames to live up to their reputation; they are known as Water Bears and Moss Piglets.
Photo sources: astrographics & bbc.co.uk
As my last post was highlighting the depressing fact that microbes are kicking our derrières in a chemical arms race, this week I’m hopefully going to alleviate any lingering doomsday gloom by examining some cases of how we have evolved resistances against infectious diseases. On that note, let’s not dwell on the fact that many of the resistances increase as a result of massive epidemics that wipe out a high percentage of a population. Instead, think of how cool it is that 95% of the population is resistant to leprosy!
The Starting Point: Population Variation
Variation within a species is the basis for evolution, as natural selection acts upon these differences. Consequently, the overall pattern of genetic diversity in a species is the result of evolutionary processes of natural selection. Demographic history such as population size and substructure, as well as migrations, mutations, genetic drift (random change in gene frequencies in a population), selective pressures, and recombination rates (creation of new combinations or forms of genes) all impact our genetic diversity . This genetic diversity is important to understand how prominent resistances come about.
Through the wide range of clinical presentations of diseases, the racial differences in severity and susceptibility to diseases, and various twin studies, researchers realized there was a correlation between our genetics and susceptibility to diseases. Human genes provide some susceptibility or, conversely, resistance to specific infectious diseases in individuals as well at the population level [4,5].
Did you know we might be moving into an era where antibiotics are obsolete? Just earlier this week there was an article in the U.S. News describing an outbreak of ‘Totally Drug-Resistant’ Tuberculosis in South Africa. In light of this increasingly urgent problem, this post is dedicated to antibiotic resistance!
What is antibiotic resistance?
Antibiotic resistance (AR) is a naturally occurring phenomenon that arises through biological and chemical warfare between microbes. DNA analyses have found proof of antibiotic resistance in 30,000 year old sediment samples, but it’s likely that the battle between antibiotics and resistance has been going on for millions of years . Bacteria and other such organisms are constantly competing for resources (or eating each other), turning the world around us into a slaughterhouse of biological warfare. It’s all very exciting, but most of us humans are completely oblivious to it.
Warning: This blog post contains descriptions of animal sexual behavior, in more detail than you probably ever wanted to read.
In honor of this week’s holiday, I thought I’d break away from diseases and delve into some of the more bizarre romance that occurs in nature (the alternative would have been to write about STDs. Trust me, this subject is better). You thought being single on Valentine’s Day was bad? Try being in a relationship as one of these creatures!
There is no truer expression of love than offering up one’s body in sacrifice for a romantic dinner. No? Well, red back spiders might disagree with you! Sixty-five percent of mating encounters end in cannibalism for this species . What is truly bizarre, however, is the fact that the male willingly offers himself up: during copulation, the male spider performs a somersault to present his abdomen to the female’s fangs! He even undergoes special muscle contractions of the abdomen to move his vital fluids out to ensure he survives as long as possible during his consumption [1,7].