Possible Resurrection of the Mammoth as early as 2018

The woolly mammoth (Mammuthus primigenius) will roam the earth again and soon, thanks to new advances in genetic engineering.  The new technology is based upon another fairly recent discovery known as CRISPR, an acronym that stands for clustered interspaced short palyndromic repeats.  Scientists discovered CRISPR when they were studying how a bacteria’s immune system works.  Viruses often attack bacteria.  To develop immunity to the viral infection, the bacteria cut and paste fragments of the virus’s DNA into its own genome.  Jennifer Douda and Emmanuelle Charpentier realized they could use this process to cut and paste desired changes into an organism’s genome.  They engineered the protein CAS9–2 RNA molecules that made it easy to cut and paste characteristics of 1 species into another species genome.  Feng Chang and Georgie Church were the first scientists to use this technology on a human cell, and now there is a big patent dispute between Chang and Douda over who deserves the monetary reward for this potentially lucrative invention.  As early as 2018, George Church of Harvard University plans to cut and paste certain characteristics of the woolly mammoth into an Asian elephant (Elephas maximus) embryo that will then be implanted in an elephant.  If this project is successful, the woolly mammoth will be reborn.

Scientists recently sequenced the genomes of 3 Asian elephants and 2 woolly mammoths.  (They were able to extract DNA from woolly mammoth carcasses preserved in Siberian permafrost.)  The Asian elephant is the closest living relative of the woolly mammoth.  The study confirmed the common ancestor of both species diverged about 5 million years ago.  The genetic evidence shows since that divergence the woolly mammoth evolved many adaptations to frigid environments.  Woolly mammoths evolved thick fur, short ears, a thick layer of fat, a hump of brown fat between the shoulders, reduced sensitivity to cold, enlarged sebaceous glands, and an altered circadian rhythm response.  Sebaceous glands secrete oil into hair for lubrication.  This made woolly mammoth fur waterproof and would have helped them keep warm in wet conditions.  The altered circadian rhythms were an adaptation to the extreme changes in day length that occur in the upper northern hemisphere.  These are the woolly mammoth characteristics Georgie Church will cut and past into an Asian elephant embryo.

Eventually, woolly mammoths could populate an experimental Pleistocene Park located in Siberia.  Herds of woolly mammoths could co-mingle with caribou, moose, horses, bison, yaks, Saiga antelope, and camels.  The foraging and trampling of all these animals compacts the soil, keeping the permafrost intact.  Scientists believe this could help mitigate the effects of global warming, so there is a practical purpose for re-introducing woolly mammoths to the environment.  I know it would be a tremendous tourist attraction and hopefully some day much of Siberia will be overrun with megafauna.

View of the experimental Pleistocene Park in Siberia.  The re-introduction of horses has increased the grassland cover here.

References:

Lynch, Vincent; et. al.

“Elephantid Genomes Reveal the Molecular Bases of Woolly Mammoth Adaptation to the Arctic”

Cell Reports 2015

Woolly Mammoth Revival

The Eurasian Steppe Mammoth (Mammuthus trogontherii) may be the same species as the North American Mammoth (Mammuthus columbi)

Eurasian steppe mammoths crossed the Bering Land Bridge early during the Pleistocene (~1.9 million years BP) and colonized North America.  They ecologically replaced stegomastodons over most of the continent but the ranges of both overlapped in Central America until the late Pleistocene.  Mammoths never colonized South America where stegomastodons continued to flourish until human hunters arrived on the scene.  Mammoths were probably better adapted than stegomastodons to the cooler more temperate climates that occurred over most of North America during the Pleistocene. Stegomastodons should not be confused with the American mastodon (Mammut americana) which co-existed with mammoths across most of North America for almost 2 million years.  They were able to co-exist because these 2 species favored different ecological niches.  Mammoths preferred higher drier grasslands, while mastodons were semi-aquatic denizens of wetlands.

Scientists long assumed mammoths that colonized North America evolved into a different species than Eurasian steppe mammoths.  North American mammoths of the late Pleistocene are given the scientific name Mammuthus columbi and Eurasian steppe mammoths are considered M. trogontherii.  However, a recent study of mammoth teeth determined M. columbi and M. trogontherii should be considered the same species.  The authors of this study think teeth of the Columbian mammoth originally used to compare with the teeth of the Eurasian steppe mammoth were from older individuals, thereby misleading scientists into thinking M. columbi was a different species.  The differences could be explained by normal wear and tear that one would expect from older animals.

2 teeth from a Eurasian steppe mammoth. (On sale for 840 British pounds)

Columbian mammoth tooth.  2 scientists determined from an analysis of teeth that the Columbian mammoth of North America and the Eurasian steppe mammoth were the same species.

Eurasian steppe mammoths evolved into woolly mammoths (M. primigenius) about 370,000 years ago during an harsh Ice Age.  Woolly mammoths also crossed the Bering Land Bridge, and as I mentioned in my previous blog post, hybridized with Columbian mammoths wherever the ranges of the 2 species overlapped.

Reference:

Lister, A. M., and A.V. Scher

“Evolution and Dispersal of Mammoth across the Northern Hemisphere”

Science 2015

The Southern and Northern Range Limits of the Columbian Mammoth (Mammuthus columbi)

If the U.S. government exiled me for some reason, I’d consider moving to Canada or Costa Rica.  I’d probably choose the latter because the weather is nicer.  I fantasized about moving to Costa Rica a few months ago and even searched online for a house.  I found a nice home for sale at a price similar to the value of my current residence in Augusta, Georgia.  Monkeys and coati-mundis frequent the backyard there.  Alas, the satellite television service is reportedly poor, so I might not get to watch the Georgia Bulldogs play football.  I suppose, if I made this fantasy come true, I’d have to rename my blog–Costa Rica Before People.

Central America provided a diversity of habitats for many species of megafauna during the late Pleistocene.  During full glacials tropically heated water pooled near the equator and did not circulate into the North Atlantic.  The region stayed warm year round and was covered with various types of tropical forest.  Yet some grasslands must have existed because fossil evidence of the Columbian mammoth, a grazer, has been unearthed at a site in Costa Rica referred to as the Hacienda Silencio (Silent Estate).  (From what I can determine online this site sounds like an upscale resort.)  This is the southernmost known range limit of the Columbian mammoth.  A deep belt of tropical forests, inhospitable to Columbian mammoths, must have prevented this species from moving farther south and colonizing South America.  A specimen identified as a mammoth was found during the 1930s in Guyana, but that specimen has been lost, and it’s likely a misidentification.  Instead, the specimen probably represented another species of proboscidean that did colonize South America.

There were 4 genera of proboscideans living in Central America during the late Pleistocene–the aforementioned Columbian mammoth, as well as mastodon, stegomastodon, and gompothere.  The remains of mastodon and gompothere have never been found together in the same fossil site in this region, leading researchers to believe they occupied different types of habitat.  Mastodons preferred lowland aquatic habitats, while gompotheres lived in higher drier forests.  Columbian mammoths favored savannahs and prairies but could adapt to some wooded environments.  The wide geographic range of the Columbian mammoth is evidence that it was a particularly adaptable species, capable of surviving in many different habitats.

Famous Charles Knight painting of Columbian mammoths.  Most of the google images of this species depict it without fur.  Columbian mammoths probably had fur because they occurred all across North America and could endure all sorts of climatic conditions.

Range maps of Columbian and Woolly mammoths.  Fossil evidence of Columbian mammoths has been found farther south than this map indicates.  Genetic evidence suggests these 2 species occasionally interbred where their ranges overlapped.

Columbian mammoths lived as far north as southern Canada.  Genetic and morphological evidence suggests that it hybridized with woolly mammoths (Mammuthus primigenius) in the northern part of its range where it overlapped with its northern cousin.  Some mammoth specimens found in the Great Lakes region have been given the species name, Mammuthus jeffersonii.  Scientists suspect this purported species is merely a Columbian and woolly mammoth hybrid.  Columbian mammoths were substantially larger than woolly mammoths, so these hybrids were nearly all the result of male Columbian mammoths copulating with female woolly mammoths.  Male Columbian mammoths overpowered male woolly mammoths in battles over mating rights.  The same scenario holds true today in Africa where larger savannah elephants (Loxodonta africanus) occasionally mate with smaller forest elephants (L. cyclotis).  There is also a case of an African elephant successfully mating with an Asiatic elephant (Elephas maximus) in captivity.

Scientists haven’t yet conducted a genetic study to determine when Columbian mammoths diverged from woolly mammoths.  The ability of the 2 species to hybridize suggests this divergence was more recent than the fossil evidence suggests.

References:

Cabrales-Arroyo, Joaquin; et. al.

“The Proboscideans (Mammalia) from Mesoamerica”

Quaternary International July 2007

Enk, Jacob; et. al.

“Complete Columbian Mammoth Metagenome Suggests Interbreeding with Woolly Mammoths”

Genome Biology 2011

Lucas Spencer; Alvarado Guillermo, Edwardo Vega

“The Pleistocene Mammals of Costa Rica”

Journal of Vertebrate Paleontology 1997

 

The Saltville Fossil Site in Virginia

A dense forest of white pine, spruce, fir, and oak  grew in the Saltville River Valley 17,000 years ago.  There were also some alder swamps and wet sedge meadows, but unlike in the regions to the south and west of this locality, there were no prairies or open woodlands.  The Saltville River Valley is located in southwestern Virginia and during the last Ice Age, this area was much colder than the region located immediately to the south.  The oceanic Gulf Stream that carries tropically-warmed water north as far as the Canadian coast today, instead only went as far north as the Virginia/North Carolina border during the Ice Age.  This meant dry land temperatures in what is now Virginia were as much as 10-15 degrees Fahrenheight  cooler on average than those about 50 miles  further south.  Consequently, the environment in the middle Atlantic States decisively differed from most of southeastern North America.

Location of the Saltville River Valley.

Saltville, Virginia is located in a beautiful valley.  A large lake, known as Lake Totten, covered much of the valley from ~13,500 BP-~8,500 BP.  Salt mining operations have upset the hydrology here, and today as much as 20% of the valley is underwater. 

The Ice Age began waning about 15,500 years ago.  The Laurentide Glacier slowly receded, and the melting ice increased the flow of water into the Saltville River.  Sediment carried by the increased flow formed a mud dam in the Saltville Valley gap, causing the water to backflow and create Lake Totten.  The outflow was captured by another river.  Many of the species of large mammals that lived in North America then were attracted to the abundant salt springs in the area.  The individuals that happened to die during periods of increased sediment flow were buried by mud and preserved for fossil enthusiasts and scientists to find thousands of years later.

An assortment of fossils found at Saltville.  The animals were buried by mud carried by river surges resulting from melting glacial ice to the north.  Paleontologists have to pump out groundwater from their excavation sites here.  Salt mining operations have caused much of the land to flood.

The Saltville fossil site is the most southerly known location where specimens of woolly mammoth (Mammuthus primigenius) have been excavated.  Specimens of Columbian mammoth (Mammuthus columbi) have been excavated here too, showing the 2 species co-existed in some locations.   The 2 species of mammoth have also been found together at a site in South Dakota.  Columbian mammoths ranged much farther south than woolies, having occupied territory as far south as what today is Florida.  Other megafauna species recovered at Saltville include mastodon, Jefferson’s ground sloth, woodland musk-ox, bison, stag-moose (Cervalces scotti), caribou, white tail deer, horse, and giant short-faced bear (Arctodus simus).   Scientists have yet to publish their findings on the smaller species of animals discovered in the fossil deposits.

Puncture mark on a mammoth heal bone made by a giant short-faced bear’s canine.

Gnaw marks on an ankle bone, probably made by a dire wolf.

A mammoth heel bone excavated from this site has a puncture mark that matches the canine of a giant short-faced bear.  This species of bruin is thought to have specialized in kleptoscavenging.  (See: https://markgelbart.wordpress.com/2012/12/10/bearzilla-the-biggest-bear-in-history/) The ankle bone of the same animal was gnawed on by a canid, probably a dire wolf.

A study of the bone chemistry of fossil herbivores from this site had an unexpected result.  All the herbivores living in this region then ate C-3 (carbon 3) vegetation–trees, shrubs, and some herbs.  Even species such as mammoths, bison, and horses that predominately subsisted on C-4 vegetation (grass) elsewhere were restricted to a diet of twigs, leaves, bark, and herbs here.  This is considered evidence that prairies were absent from this particular region during this time period.  The authors of this study admit their findings weren’t sufficient evidence to make any conclusions about megafauna extinctions.  Yet, they suggested competition between grazers and browsers for the same resources may have caused megafaunal extinctions.  I disagree with this conjecture.  Instead, I think their findings are strong evidence against climate change as a cause of megafaunal extinctions because the study shows these animals were not picky eaters and could adapt well to changing environmental conditions.

Humans apparently killed, butchered, cooked, and ate a mastodon at Saltville 17,000 years ago.  Archaeologists found cut marks on a mastodon’s bones as well as congealed grease that could only be the result of cooking.  They also found heat-cracked rocks used in the cooking process.  Pre-Clovis artifacts found associated with the mastodon bones include 2 sandstone knives, a chert blade made out of rock transported from some distance away, and flakes (debitage) from tool-making.  The site was occupied 3 times prior to the Clovis era.  The most recent pre-Clovis horizon dates to about 15,000 years ago and includes a midden containing hundreds of shells from giant floater clams.  This species of freshwater mussel grows to 10 inches long and used to be abundant in North American waters before modern day pollution and river damming.

Giant floater clam (Pyganodon grandis).  I’ve never eaten a freshwater mussel, but they smell like delicious oysters.

Saltville is not a new site.  Thomas Jefferson knew about fossils found here.  Scientists have been excavating fossils off and on here for over 200 years.  A team from East Tennessee State completed the most recent excavation this year.  They visited local amateur fossil collectors to examine their specimens, and they are surveying caves in the nearby mountains in the hopes of finding more fossils to help piece together the regional late Pleistocene ecology.  We haven’t heard the last about this site.

References:

France, Christine; et. al.

“Carbon and Nitrogen Isotopic Analysis of Pleistocene Mammals from the Saltville Quarry (Virginia USA): Implications for Trophic Relationships”

Paleogeography, Paleoclimatology, Paleoecology 249 2007

Schubert, Blaine; and Steven Wallace

“Late Pleistocene Giant Short-Faced Bears, Mammoths, and Large Carcass Scavenging in the Saltville Valley of Virginia, USA”

Boreas 38 (3) August 2009