Equine Science FAQ

Here are some frequently asked questions and the corresponding answers related to the Equine Science lecture page.

Q: I still do not completely understand confirmation bias.

A: It is important to have some understanding of confirmation bias to best be able to critically evaluate information, particularly information obtained through scientific studies. Here is a link to a recent article entitled “Meta-assessment of bias in science” that was published in the Proceedings of the National Academy of Sciences, a reliable and respectable source. Here is another simpler explanation and discussion from the Psychology Today website.

Q: There were several questions about the concept of explosive adaptive radiation and what caused it.

A: The explosive adaptive radiation occurred during the Miocene epoch.  You can read a basic and useful description of adaptive radiation on Wikipedia. The cause of the explosive adaptive radiation of the horse is theoretical, but was likely due to the match between the earth’s cool and dry climate, the expansion of grasslands, and the horse’s digestive anatomy being so well suited to this particular environment.

Q: What is the difference between grazing and browsing?

A: Browsing is a feeding strategy that focuses on relatively low quantity / high quality foods. A good example would be the leaves on bushes or trees. Grazing, on the other hand, is a feeding strategy focused on eating forages, like grasses and legumes that tend to be high quantity / low quality foods.

Q: What is equine science?

A: Equine science is an approach to answering questions or solving problems related to horses using the scientific method and achieved through study and practice of different areas like nutrition, exercise physiology, reproduction, genetics, etc.

Q: There were a lot of questions about the evolution of horses’ teeth. Here are some of my thoughts regarding the answers to some of these questions.

A: Horses’ teeth continue to erupt for 7-10 years after they first appear. This means that when horses get older than 15 years of age, their teeth are simply wearing down. Most horses in the wild will not live into their 30’s and 40’s, but there are more and more horses that we care for that do live this long. These horses will likely require special care to account for the fact that their teeth are likely to not be as effective as they once were. These older/senior horses may benefit from feed that is softer or more digestible. It is also interesting to note that research has shown that horses chew hay and grain differently. Their jaw moves in a larger circular motion and they chew more when fed hay versus grain. While it has not been quantified, this may result in different tooth wear patterns in horses fed high grain or hay diets.

Q: How do horses in the wild meet their nutrient and energy requirements?

A: Horses in the wild have a wide range of plant material available to them. Usually they are grazing on thousands of acres of land. Their grazing strategy is one of a high intake and high rate of passage. The basic idea is that if they can eat enough of a poor quality forage they can meet the nutrient and energy requirements. It is also likely true, that horses in the wild often do not meet their requirements. Under these conditions they may lose body condition, and in extreme circumstances, even die.

Q: Will horses adapt or evolve to the current conditions that we keep them in?

A: I thought this was a great question, and I am not sure that I have a good answer. Evolution does not occur at a constant rate, and is dependent on many environmental variables. We do influence the evolution of the modern day horse through the genetic selection that is a part of breed development. We may also inadvertently select for horses that survive better under the management practices we use. For example, perhaps we are slowly selecting for horses that are better at eating large grain meals. Generally, we understand that evolution takes a long time for measurable change to occur. Consider that we have only been keeping horses the way we do today for 500 to 1,000 years. I think measurable changes related to this environment are likely to be present for at least another 10,000 to 100,000 years.

Q: What is incorrect about the horses in the Epsom Derby painting (1821)?

A: The answer in short is that the horses’s gaits are incorrectly painted in this picture.  When we get into the gaits lecture in a few weeks, we will discuss gaits and the way a horse moves. This will provide insight into how inaccurate the painting is in regard to the way the horses are moving.  It is very interesting to see how throughout history, a horses’ gait has been sculpted, painted or generally depicted with inaccuracies.

Q: Why did horses evolve from a three toed animal to a single toe? What happened to the other digits as the horse evolved?

A: There are several theories as to why this occurred. The most important thing to understand is that this adaptation happened over tens of millions of years. The most likely theories suggest that this adaptation developed to facilitate the horse traveling great distances and avoiding predation. Traveling great distances allowed the horse to take advantage of the nutrient rich grasslands. Horses that had less or smaller side digits(and a larger primary digit or eventual hoof) were more successul in the environment and passed their genes along.  Those with longer multiple side digits were not as successful.  Over tens of millions of years, this resulted in those additional digits disappearing.

Q: Who were the first humans to domesticate horses and where in the world were they domesticated?

A: The earliest archaeological evidence of horses’ transition from prey to pets, unearthed several years ago at a site in Kazakhstan associated with the prehistoric Botai culture, dates back to 3500 B.C. In recent years, many scholars have embraced the hypothesis that the Botai or other inhabitants of the Eurasian Steppes became the first people to tame the wild horse, between 4,000 and 6,000 years ago.

Q: How does an Armsby calorimeter work and what is it used for?

A: A calorimeter is an instrument used to measure the amount of heat that is absorbed or released during physical and chemical processes. This allowed Armsby to measure how much energy an animal was able to derive from a certain food source. The Armsby calorimeter is explained very well(including a video featuring Dr. Staniar!) in a Penn State news article and has a page devoted to its historical explanation on the Penn State Animal Science website.