How Hurricanes Impact Natural Selection

Many of us are familiar with hurricanes and the disaster they cause. This last season brought some of the worst storms ever seen, and the trend indicates more will be coming.

Not only should we be concerned with the devastation this will have on the human population, but we must turn our attention to other species as well.

So when you see this video, don’t be so surprised.

Yes, that’s right. For the sole purpose of science, researchers put lizards on a leaf blower and tried to kick them off. Turns out they are pretty good at riding along.

But, why would scientists torture innocent lizards?

Well, they really didn’t. As it seems, lizards are remarkably talented at staying put when necessary, even during high force wind events, such as a hurricane. Scientists had an incredibly hard time knocking the lizards off (and if they did fall off, there was padding in place to keep them safe).

Biologist Colin Donihue, after recently visiting small islands in the Caribbean and studying the anole lizard, was given a remarkable opportunity.

Not long after his team’s departure, two hurricanes hit the islands, both with wind speeds clocked above 200 kilometers per hour.

The team returned as soon as the coast was clear, and examined the lizards present immediately after the devastating storms.

What they found was interesting. After a quick examination, it was noted that the lizards most present after the storm had larger toepads, longer forelimbs, and shorter hind limbs than what was measured before the storm.

This gave the team from Harvard an idea. Could they replicate a hurricane like experience under a controlled setting and actually show if these traits are favorable? Since I have already shown you the video…. the answer is yes, they could.

Image result for toe pads of lizards
An example of a toepad belonging to a lizard (gecko in this case). Source

It is thought that these traits allow lizards who live in such a climate to latch onto branches in small bushes and hold on for dear life until the storm has passed.

What makes this particular study so unique, is the chance to study a population before a large event, and immediately after. The scientists were able to directly measure the difference between the species and discover what sort of traits enhanced survival. This allows a direct measurement of natural selection, the idea of how evolution works.

While there many other possibilities besides a hurricane that could drive a lizard to have larger toepads or shorter hind limbs, the natural selection process is still present.

More importantly, this small study could provide a glance into how climate change affects species. With the heating of the oceans due to astronomically high temperatures, weather patterns change dramatically. This includes the frequency of large scale storms such as hurricanes.

With hurricanes becoming more common in the tropical areas, such as the Caribbean, this forces animals such as the anol lizard to either adapt or suffer. While it seems this remarkable lizard has developed a method to out ride the storms, and probably give them a severe advantage at rodeos if given the chance, much yet is to be discovered as to how well species adapt with the increasing temperatures, ocean acidification, and frequency of severe weather patterns.

 

Thank you for reading this fun, quick blog!

If you have any questions, comments, concerns, or suggestions, please email us directly or post a comment below. You can also reach out to us on Facebook and Twitter.

And as always, be curious and stay mindful!

 

Sources:

  1. https://www.nature.com/articles/s41586-018-0352-3
  2. https://www.nature.com/articles/d41586-018-05821-7
  3. https://www.nature.com/articles/d41586-018-05822-6 (original video source)
  4. Featured Image- https://www.youtube.com/watch?v=Dx3xgSBjbzk

 

 

 

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Homo Naledi, The New Ancestor

H. naledi cover photo
Source

After the relatively recent discovery of Homo naledi, much has been released about their habits and lifestyle.

For those of you that have not heard about this wonderful fossil excavation, here is some background.

In 2015, a remarkable collection of fossils were found in South Africa(1). These bones were quickly categorized as human-like. While several other human-like species have been discovered (Homo habilis, Homo erectus, just to name a few),non resembled the bone structure of the new specimens. Thus, these bones have been classified as a new addition to our ancestral map.

Cross-section_of_the_Rising_Star_Cave_system_Dinaledi_Chamber.svg
Diagram of Rising Star cave system and Dinaledi Chamber where 15 Homo naledi specimens were discovered. Source

They were given the name Homo naledi. Homo refers to the genus of the species (which we are apart of) and naledi translates to “star” in english (named after the cave where they were found). The unique quality of these fossils was not just the knowledge of a new species, but also what we have learned from them. This particular excavation gave scientists a unique understanding of the behavior of the species. Within the Rising Star cave network, 15 different specimens were located in the same cave, making it the largest assembly of human like fossils discovered in Africa (1).

Note: The original study, located here, discusses the specifics of the fossils found. If you wish to learn more about cranial size, hand shape, and how they compare to other Homo and non-Homo descendents, I recommend reading the article. If you are curious on how H. naledi fits into the current model of human ancestry, stay tuned. This whole topic will be covered in a future blog.

Part of the mystery of H. naledi is the placement of the bodies. Having 15 of the same species within such a small cave structure begs the question of how they got there in the first place.

This has been a hot topic since the discovery, and currently there are two bodies of thought:

The first, suggests that the bodies of the dead were placed as a sort of burial (although the bodies were not actually buried). There are no other fossil types within the cave (except a lone owl), which eliminates the hypothesis of a predator’s cave, and no signs of water or dirt to suggest body movement through river systems or mud slides. Dr. John D. Hawks, a prominent anthropologists, suggests that the bodies were indeed placed deliberately (5).

Another school of thought, related to the first, believes that body placement may have been related to a ritualist demonstration (in this case, not a religious ritual). This hypothesis however, has been placed under scrutiny. At the time of this blog post, no tools or other materials suggest a ritual of any kind, and no evidence on fossils suggest violent deaths that may be associated with rituals (6).

In addition to learning about burial rituals, there is also much left to learn from H naledi as far as their lifestyle, i.e. their diet.

Since the stomach of naledi has been decomposed for an extremely long period of time, we can gather much information from their teeth.

It may seem weird, but teeth have been used extensively to gain insight on the lifestyle of extinct species. A recent study has been released doing just that with H. naledi.

Scientists in the UK first looked at the naledi teeth, and immediately discovered a unique quality; they were chipped. But this didn’t occur from damage over time, rather the chipping occurred before the specimens died (called antemortem)(2).

TEETH
Example of  the “chipped” teeth of H. naledi. Source

What makes this unique is that this has never been seen in other fossils of ancestral species, or even in primate species. 44% of the teeth recovered had damage to the enamel occurring before death. These rates by far surpass other teeth examined from our lineage.(2)

Interestingly, scientists have determined that the chipping has occurred due to their diet. By determining which type of teeth have the most chips (incisors, premolars, etc), the researchers were able to infer that a high “grit” diet from roots or tubers that were commonly eaten.(2,4)

While it may not be “front page news” on what H. naledi ate specifically, it does provide another piece to the puzzle. As we continue to learn and discover more about these extinct ancestors, we will be able answer other questions related to evolution and the development of life on our planet.

As always, thank you for reading. If you have questions or comments, please email us directly at copernicuscalledblog@gmail.com. You can also reach us on Facebook, Twitter, and Tumblr.

 

Remember to always be curious, and stay mindful!

Written By: Cody Wolf

Sources

  1. Berger, Lee R. Homo naledi , a new species of the genus Homo from the Dinaledi Chamber, South Africa. eLife, eLife 2015;4:e09560 DOI: 10.7554/eLife.09560  https://elifesciences.org/articles/09560.
  2. Towle, Ian. Behavioral Inferences from the high levels of dental chipping in Homo naledi. American Journal of Physical Anthropology. 2016. DOI: 10.1002/ajpa.23250. http://onlinelibrary.wiley.com/doi/10.1002/ajpa.23250/abstract;jsessionid=C151DCA7FF6D8C04BBBD29023969E3F8.f02t02
  3. https://en.wikipedia.org/wiki/File:Cross-section_of_the_Rising_Star_Cave_system_Dinaledi_Chamber.svg
  4. Belgastro, Giovanna. Continuity or discontinuity of the life-style in central Italy during the Roman imperial age-early middle ages transition: Diet, health, and behavior. American Journal of Physical Anthropology. 2006. DOI: 10.1002/ajpa.20530.http://onlinelibrary.wiley.com/doi/10.1002/ajpa.20530/abstract
  5. Drake, Nadia (15 September 2015). Mystery Lingers Over Ritual Behavior of New Human Ancestor. National Geographic News.http://news.nationalgeographic.com/2015/09/150915-humans-death-burial-anthropology-Homo-naledi/
  6. Ghosh, Pallab (10 September 2015). New human-like species discovered in S Africa. BBC News. http://www.bbc.com/news/science-environment-34192447

New Research Suggests T-Rex is Unable to Hug AND Run

Cody Wolf

Most everyone has probably seen at least one installment of the Jurassic Park series. For those of you in the small population, the main plot of each movie is running away from a ferocious predator, usually a Tyrannosaurus Rex or some similar carnivorous dinosaur. The protagonist typically has the job of running, driving, or otherwise hiding to avoid being eaten alive.

Much like in the movies, the world of dinosaurs, at least in the research of dinosaurs, has thought that a T-Rex had the capability to run and catch fast prey.

Certain research articles suggest that dinosaurs like a T-Rex could run upwards to 50-60 kilometers per hour, or about 37 miles per hour(Paul, 1998). That’s pretty damn fast.

However, a recent study published in Peer J suggests that a T-Rex was actually incapable of running. In this particular study, running was defined as a gait that would be running without having both feet off of the ground at the same time, for example a horse gallop.

So with Velociraptors being the actual size of our modern turkey, and a T-Rex being unable to run, Jurassic Park may not be such a bad idea after all….Just kidding.  

But how in the world can a T-Rex be incapable of running?

The study that previously mentioned a high speed for the T-Rex suggested so due to their long and strong legs and specialized hip structure. This new study indicates that the legs of a T-Rex was actually the reason why they couldn’t run. In fact, their top speed reached about 12 mph.

How can two studies contradict each other when they are looking at the exact same information?

The answer of course, is in the details.

 

If you get a chance to read the Peer J article (which I always recommend), the introduction focuses on previous studies and the various mechanisms used to determine speed. While we don’t have enough time to go over all of them, I figured one may be beneficial to our readers.

Blog #2 T-Rex Can't Run

Gregory S. Paul published an article in 1998 suggesting that a T-Rex, with its specialized pelvis and leg structures being similar to modern tetrapods (four legged creatures), would be able to run at a reasonable pace. In case you are unfamiliar with the running patterns of different species (which I was until researching for this article), it’s important to note that a Rhinoceros, having a similar pelvic and leg structure is able to run at a reasonable pace. They are also quite large. Meanwhile, an elephant, which is more comparable in weight to a large T-Rex has a very different bone structure and is designed specifically for walking (see figure above). Elephants also have an ankle that prevents mobility (which differs from ours, a Rhino’s, and a T-Rex) and have a “flat” pelvis more similar to humans. In addition, examining the shape and orientation of the hip bones of Tyrannosaurus suggests that it is better suited to maintain the weight of its owner and can give it the ability of running.

Paul continues to discuss the correlations of femur bone length and speed where there appears to be a positive correlation between speed and the length of your thigh bone. He also goes on to discuss how bone shapes and certain structures can suggest how fast an animal is able to run.

He then focuses on other studies that suggest a T-Rex is unable to run. One in particular highlights the frailty of the leg bone, and how running could not be possible with the average weight of these gigantic creatures. Paul points out that the femur of a T-Rex may be able to support more weight than expected with these models, largely due to the thicker walls of the femur. He also mentioned discrepancies with the weight they predicted and the fossils analyzed have damage that would confound the data.

As I am sure you have noticed by now, there appears to be a slight conflict in regard to the speed of our beloved dinosaur.

So what does this new study have to say?

The Paul study we just previously mentioned, and other studies that conflict with it all have one thing in common. The research is focused only on bone morphology. All of these scientists spent time studying fossil structures and comparing them to bones of modern animals to “tweak out” clues of what life being a T-Rex was like.

But there is one aspect missing; the tissue.

Blog #2 T-Rex cant run pic 2

 

Bone alone cannot work to move our limbs. Soft tissues like muscles are needed to let our bodies twist and turn. And these soft tissues can have an impact of how we can move.

Recent advances in technology have given scientists the opportunity to estimate how muscles connected to bone, and how they affected movement in extinct species. This technique is what the Peer J article primarily utilizes.

The figure above shows an estimation of various muscle structures and limb interactions might have been like for the T-Rex. By scanning the bones and calculating joint positions and range of motion, muscle structure could then be predicted.

After this, computer models can be simulated. The output from the computer simulations were able to give a maximum velocity. The answer? Eh, about 8 meters per second. The data also calculated the estimated stride of the dinosaur (at its peak about 8 meters), and the Froude number (used to compare speeds with other animals) that suggested a T-Rex can only reach a walking stride.

Additional data that focuses on the change in kinetic and gravitational potential energy also confirms that a T-Rex could not gain the energy differences to achieve a running speed.

 

My Opinion

While I think this study makes valid points, and uses technology that can estimate at a much higher efficiency than previous analyses, there is still much to weed out. Unfortunately, soft tissue does not preserve well and we most likely will not find a perfectly preserved T-Rex. However as technology increases in power, and as we work to understand how other tissues might have impacted the movement of the large dinosaurs, much more is left to be discovered. I do think this study is moving in the right direction, and gives us more information than we had previously. If you are interested in either of the articles I discussed today, the links are below. Attached here is also a link to videos the scientists produced with their program of the simulated T-Rex walking!

If you have any questions, or comments about this article or others, please do not hesitate to email us directly at copernicuscalledblog@gmail.com. You can also reach us through social media, at our Facebook and Twitter pages.

 

Remember to always be curious, and stay mindful!

 

Sources:

1.May, Ashely. Sorry, ‘Jurassic Park’ fans: The T. rex couldn’t run, new research says. USA Today, July 19, 2017. https://www.usatoday.com/story/news/nation-now/2017/07/19/t-rex-couldnt-run-new-research-says/491122001/

2. Paul, Gregory. Limb Design, Function, and Running performance in Ostrich-Mimics and Tyrannosaurs. Gaia 15. December, 1998. http://gspauldino.com/GaiaLimbdesign.pdf

3. Sellers, William. Investigating the running abilities of Tyrannosaurus rex using stress-constrained multibody dynamic analysis. Peer J. July 18,2017. https://peerj.com/articles/3420/.

4. Title picture source- https://www.pinterest.com/pin/474003929501926665/