Just imagine your neighbor getting angry and leaving a poisonous bite on your arm. This disturbing scenario could become a reality in the future, according to scientists.
How amazing is this? People evolving to grow their own venom glands?
The fascinating new research took a long hard look at salivary glands and how they wound up becoming venom glands in several animals. Since saliva is now known to be the common link, it suggests anyone having a salivary gland can develop venom in the future. This ranges all the way from rodents to people.
A study connecting venom to saliva
This remarkable study was conducted by researchers from the Australian National University and the Okinawa Institute of Science and Technology Graduate University (OIST). The team was exploring to answer an age-old question in biology: how did animals create venom glands as they evolved?
“Oral venom systems evolved multiple times in numerous vertebrates enabling the exploitation of unique predatory niches. Yet how and when they evolved remains poorly understood,” the research team stated.
Examination of genes
Since the possibilities were endless, the field had to be narrowed down. They did this by examining groups of several thousand genes having a venom release expressed in tandem with animals having venom glands. They discovered that the exact physical mechanisms and genes existed in the same old saliva glands of other animals.
“We found that overall venom gland gene expression was surprisingly well conserved when compared to salivary glands of other amniotes. We characterized the ‘metavenom network,’ a network of ∼3,000 non secreted housekeeping genes that are strongly coexpressed with the toxins, and are primarily involved in protein folding and modification.”
This means that saliva glands basically serve up empty bowls, while venom glands serve up bowls containing poison. It is not the genes or a missing mechanism; instead, it’s the actual content of what gets released from those glands – specific proteins.
Many people are unaware that venom is quite a mystery to scientists. There are several reasons for this. One reason is that it hasn’t been studied like other systems of nature. Perhaps the biggest reason is that venom is amazingly eclectic.
“While many snakes employ an oral venom system for securing prey, there are also mammals, such as shrews, and solenodons, that have evolved oral venom systems (based on salivary glands) for prey capture or defense,” scientists tell us, indicating that thousands of venomous animal species exist today.
This widespread aspect is venom is why it’s exciting to discover a common genetic ancestor. Because of this, scientists can focus on the common link between reptiles and mammals. While there are just a few venomous mammals, their venom is different from reptiles.
“For instance, salivary tissue of most mammals produce large volumes of very dilute mixtures, while snake venom glands produce highly concentrated mixtures of diverse toxins.”
Differences in nature’s poisons
This does explain why this venom link hasn’t been explored by science very often in the past. The total pool of species was just too large, and no focal point was apparent enough to justify looking closer.
“In venomous snakes, gene families have undergone greater expansions and have evolved at a significantly higher rate than in other lineages like mammals,” the research team points out, which explains why these snakes that produce high-octane venom as compared with the watered-down venom excreted by mammals with the same genetic pattern for expression.
Finally, after learning this information, we know it goes back to earlier salivary glands. Which seems to be the best place to examine the commonalities and differences among the two species groups.