Author Archives: Greg

Mammoth protein designed to be cool

Researchers were recently able to isolate and study woolly mammoth hemoglobin and compare it to the modern African and Asian elephants. They isolated the genes from DNA that code for the creation of hemoglobin, the protein that carries oxygen in our blood. This was done for both the modern elephant species, as well as from DNA from mammoth bone from Siberia. They observed some minor differences between all the species, so the researchers wondered if the difference in the mammoth’s blood might have helped it survive in cold climates.

Hemoglobin supplies our body with oxygen by carrying it around in our blood stream and then releasing it to our tissues. When our tissues need more oxygen, like for muscles that are working hard, hemoglobin more easily releases oxygen because of the higher temperatures created by the heat generated by the muscle. However, in colder temperatures, hemoglobin does not give up oxygen as easily. This is potentially a real problem in colder climates. To keep the hemoglobin to working effectively an animal might need to expend valuable energy to maintain a higher body temperature.

The researchers (Campbell et al. 2010) wondered if the slight differences in woolly mammoth hemoglobin might have been an adaptation for living in colder temperatures. They inserted the Asian elephant genes that make hemoglobin into the common bacteria, Escherichia coli, and allowed the bacteria to act on the genes, thereby making Asian elephant hemoglobin. This process is not new as it is commonly used to have bacteria produce proteins that are identical to human-made proteins, like insulin.

To get the bacteria to make mammoth hemoglobin, they needed to modify the Asian elephant genes the same way they observed, then let the bacteria make the hemoglobin of a mammoth—thousands of years after the mammoths last did it themselves. Researchers could then compare the protein of the two species directly. The result was that mammoth hemoglobin released oxygen much more effectively at lower temperatures.

Woolly mammoths from Alan Turner (2004), National Geographic Prehistoric Mammals.

Woolly mammoths from Alan Turner (2004), National Geographic Prehistoric Mammals.

Woolly mammoths were adapted to colder climates in a number of ways, such as compact bodies, small ears, short tails, and long woolly hair. This result strongly suggests that their bodies were also changed at the molecular level for life in cold, high latitude climates during the Ice Age. It would be very interesting to see if other mammoth species, such as the Columbian mammoth, for example, shared this adaptation. But I suppose that will have to wait until we can get good DNA from that species. All in good time.

Campbell, K. L. et al. 2010. Substitutions in woolly mammoth hemoglobin confer biochemical properties adaptive for cold tolerance. Nature Genetics 42:536-540.

Related posts:
Science in dinosaur movies: Jurassic Park then and now

New cave art found in Romania

It is well known that humans in caves in Europe began painting scenes of animals and humans on cave walls over 30,000 years ago. Over 300 sites with cave art have been found, mostly in Western Europe in places such as Chauvet and Lascaux in France and Altamira in Spain.

This summer, a team of French researchers reported a new cave with art from Romania. This Central European site suggests that the prehistoric societies across Europe were linked by a common artistic culture.

A group of spelunkers were exploring Coliboaia Cave when they spotted the cave art. Some of the drawings can only be reached by using diving gear and navigating through very cold underground water-filled spaces.

The images of Coliboaia Cave include bison, a horse, two bear heads, and two rhinoceros heads. The style of the art is very similar to the styles known from western European caves.

Images of cave art in Coliboaia Cave, Romania

Images of cave art in Coliboaia Cave, Romania. Credit: Andrei Posmosanu/Romanian Federation of Speleology.

The best guess of the researchers currently is that the cave art is between 23,000 and 35,000 years old, but radiocarbon dates might help resolve the date. Plans are underway to conduct more thorough research on the site in the near future, but the remote location makes it challenging.

This post is a summary of this story.

Two dinosaurs become one

Earlier this year a paper was published (Scannella and Horner 2010) on one of the most well-known dinosaurs of the Late Cretaceous, Triceratops, updating our understanding of not only this dinosaur species, but also maybe influencing our view of many other dinosaur species as well.

Triceratops

Triceratops as mounted at the Carnegie Museum of Natural History

Triceratops was first described in 1889 by O. C. Marsh, and has become one of the best represented dinosaur species in terms of numbers of fossils recovered. Their remains are very common in the Hell Creek Formation of Montana and the Dakotas. And, Triceratops has been known by practically every kid for the last 100 years, being well represented in dinosaur movies and dinosaur toys the world over.

Triceratops is best known for its three horns and neck frill of bone. Torosaurus, another dinosaur that is obviously related to Triceratops because of its similar appearance, was also first named by Marsh in 1891. It is found in the same geologic units in the same region, but is much less commonly found. Torosaurus was much larger than Triceratops, and had large openings in the neck frill, and its horns pointed more anteriorly.

So, for over 100 years paleontologists thought there were at least two species of horned dinosaurs in these beds. But scientific understanding makes progress. In the early “bone rush” days of the nineteenth century the game was naming new species. Today, there is a trend of relooking at those species to see if they are in fact different.

Torosaurus

"Torosaurus" mount at the Milwaulkee Museum, now should be called Triceratops.

This is where the new study comes in. The authors examined Triceratops and Torosaurus and questioned whether they might not be the same species, but at different life stages. It has become apparent that individuals of a species can change a great deal over their lifetimes. A newborn human does not look much like an adult in body proportions, for example. If past species also changed significantly over their lifetimes, the different stages could easily be mistaken as completely different species. And that seems to be the case here.

By looking closely at the trends of skull shape and indicators of maturity, Scannella and Horner believe that in fact Torosaurus individuals are older and more mature individuals of Triceratops. This means that later in their development individual Triceratops specimens changed significantly as they reached maturity, developing the large openings in the neck frill and increasing in overall size.

The implications for other dinosaur species are clear. If individuals can change dramatically during their lifetimes as they mature, perhaps there are many named dinosaurs that are not truly different and unique species, and we need to match youngsters with adults. No doubt this will keep paleontologists busy for the next 100 years.

And in case you are worried, the name Triceratops will remain, since it was the first name given to the species that we now realize includes those individuals that one were called “Torosaurus.” So, despite some headlines Triceratops did (and still does) exist!

Scannella, J. B., and J. R. Horner. 2010. Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny. Journal of Vertebrate Paleontology 30(4):1157 – 1168.

I am a paleontologist

I love the science of paleontology for many reasons. The science combines so many other areas of study into one bundle, such as geology, biology, functional morphology, evolution, stratigraphy, and systematics.

Not only that, dinosaurs and other prehistoric animals are just fun! And being fun, paleontology is a great way to introduce people to science in an engaging way. How many young people start their interest in science by learning about dinosaurs, and say they want to be a paleontologist when they grow up–a bunch!

Well, someone shared this video with me and I love sharing it with you. Enjoy! (you may need to scroll down).

Related Posts: check them out.

Dangerous animals—spiders

In this installment of the Dangerous Animals series we look at a group that is very misunderstood, and often erroneously indicted for being dangerous—spiders. In the summary chart of dangerous animals, summarized from various sources, spiders are accused of causing 6 deaths a year, on average, in North America. This is more deaths than caused by bears, mountain lions, and wolves combined, and I am highly suspicious of the figure.

In his review of the Centers for Disease Control and Prevention (CDC) data, Langley (2005) summarizes death by all sorts of wild animals, and spider bites have their own classification code, suggesting that the medical community has decided it is worth watching for. For example, the data suggest that between 1991 and 2001 there were 5 fatalities by alligators, and a whopping 66 deaths by spider. People seem to be dropping dead left and right from spider bites. What gives?

In North America, there are two types of spiders known to cause medically significant envenomations in humans: the widows and the recluse. Let’s look at each.

Latrodectus, the Black Widow

Latrodectus, the black widow

Latrodectus, the black widow, showing a characteristic pose, upside down in the web.

There are currently 30 species of spiders within the genus Latrodectus, commonly called widows in North America. The species are distributed world-wide and are on every continent except Antarctica. The venom of the widow contains neurotoxins that inhibit neurotransmission. The spiders like dark and quiet places, with bites occurring when people unintentionally grab or sit on the spider, perhaps under a porch, on lawn furniture, in the tool shed, or in gloves or other item clothing. In the past bites sometimes occurred in outdoor toilets. Symptoms of bites tend to be local and radiating pain, and sometimes back, abdominal, and chest pain, sometimes accompanied by fever, agitation, hypertension, and interestingly, priapism (Vetter and Isbister 2008). People have described it to me like a case of the flu. Untreated, symptoms can last from hours to days. Despite their infamy, death is very uncommon.

Loxosceles reclusa, the Brown Recluse

Loxosceles reclusa, the Brown Recluse

Loxosceles reclusa, a Brown Recluse female guarding her egg sac on a cardboard box in Kansas.

Few spiders generate as much passion and aversion as the brown recluse (Loxosceles reclusa). I currently live in an area where black widows are extremely common, and local people are very casual about them, but are terrified of the brown recluse. I have done many educational programs where I have displayed live spiders, including black widows, and unvaryingly I am treated to several stories by visitors about how they (or someone they know) were bitten by a brown recluse, usually with very bad consequences. (I literally had one person tell me that his aunt had her entire arm removed because of a bite). The thing is brown recluse spiders do not live here! Nothing generates fear like the unknown.

Prior to living where I do now, I lived in an area with gobs of brown recluses, and the people there were generally nonchalant about their presence, as there were almost no cases of bites resulting in horrible wounds.

Distribution map of species within the genus Loxosceles, including Loxosceles reclusa, or the Brown Recluse

Distribution map of species within the genus Loxosceles, including Loxosceles reclusa, or the Brown Recluse (from Vetter 2008).

To be clear, Loxosceles is confirmed to have bitten people and caused wounds that in rare cases take a long time to heal and can leave disfiguring scars, or even death. They are a spider of medical concern. But, having said this, the threat is far over blown.

They are named “recluse” because they like very quite areas, and can frequent homes and storage sheds in quite places. They like corners of basements, and particularly cardboard boxes. Sometimes they crawl into clothing and shoes left on the floor or in the closet. Like with the widows, people are most often bitten when they catch the spider between their body and where the spider is—the bite is defensive.

In a majority of cases, the bite results in local discomfort and nothing more. In some cases a larger wound forms that is tender, but most of these heal with minimal medical intervention, usually within days. Sometimes the wound heals slower, and in rare instances does grow large and can leave a scar. And in very rare cases (<1%) there are more significant systemic issues that can affect major organs and cause death. (Vetter and Isbister 2008).

As mentioned, I lived in an area with known recluse populations. In fact, in one case, 2,055 individual recluse spiders were captured in 6 months from one home in Kansas where the family lived for many years without a single incident attributed to the spiders (Vetter 2008). However, popular perception about these spiders is very different. Why is this?

The most likely explanation is that when the recluse was implicated in bites the most extreme cases got widely reported, heightening awareness in the public and medical community. Diagnoses of recluse bites have become common place, often in areas where the spiders have not been found in the wild, and usually without clear evidence that the symptoms presented were actually caused by a spider, or any other bite for that matter. For example, in Florida, an area without a known population of recluses, during a six year period, 844 brown recluse bites were reported: 124 by medical personnel, 198 by people seeking information about bites, and 522 from people reporting bites treated at a non-healthcare facility (Vetter and Furbee 2006). Physicians are thus occasionally guilty of “practicing Arachnology” by identifying bites, and even spider species, from clinical symptoms alone. The truth is, there are numerous conditions that have been, or could be, misdiagnosed as a recluse bite (Vetter 2008) (see below).

Given the obvious over-diagnosis and misdiagnosis of spider bites, and of recluse bites in particular, I find the assertion that 6 deaths a year in North America are caused by spiders to be highly doubtful. At the very least, this is an undeserved slam against our eight-legged friends, and at worst is misleading the public and medical community, causing potential misdiagnoses and poor treatment choices.

Conditions that have, or could be, misdiagnosed as a bite from a brown recluse (Loxosceles reclusa), from Vetter 2008.

Infections

Atypical mycobacteria

Bacterial

– Streptococcus

– Staphylococcus (especially MRSA)

– Lyme borreliosis

– Cutaneous anthrax

– Syphilis

– Gonococcemia

– Ricketsial disease

– Tularemia

Deep Fungal

– Sporotrichosis

– Aspergillosis

– Cryptococcosis

Ecthyma gangrenosum (Pseudomonas aeruginosa)

Parasitic (Leishmaniasis)

Viral (herpes simplex, herpes zoster (shingles))

Vascular occlusive or venous disease

Antiphospholipid-antibody syndrome

Livedoid vasculopathy

Small-vessel occlusive arterial disease

Venous statis ulcer

Necrotising vasculitis

Leukocytoclastic vaculitis

Polyarteritis nodosa

Takayasu’s arteritis

Wegeners granulomatosis

Neoplastic disease

Leukemia cutis

Lymphoma (e.g., mycosis fungoides)

Primary skin neoplasms (basal cell carcinoma, malignant melanoma, squamous cell carcinoma)

Lymphomatoid papulosis

Topical and Exogenous Causes

Burns (chemical, thermal)

Toxic plant dermatitis (poison ivy, poison oak)

Factitious injury (i.e., self-induced)

Pressure ulcers (i.e., bed sores)

Other arthropod bites

Radiotherapy

Other Conditions

Calcific uremic arteriolopathy

Cryoglobulinemia

Diabetic ulcer

Langerhans’-cell histiocytosis

Pemphigus vegetans

Pyoderma gangrenosum

Septic embolism

Related posts:
See the rest of the Dangerous Animals series
Pesky house bugs–bed bugs

References:

Langley, R. L. 2005. Animal-related fatalities in the United States–an update. Wilderness & Environmental Medicine 16:67-74.

Vetter, R. S. 2008. Spiders of the genus Loxosceles (Araneae, Sicariidae): a review of biological, medical and psychological aspects regarding envenomations. The Journal of Arachnology 36:150-163.

Vetter, R. S., and R. B. Furbee. 2006. Caveats in interpreting poison control centre data in spider bite epidemiology studies. Public Health 120:179-181.

Vetter, R. S., and G. K. Isbister. 2008. Medical aspects of spider bites. Annual Review of Entomology 53:409-429.