Red Deer Cave People: a new human species?

Posted on March 27th, 2012 in Evolution,Science by Robert Miller

Cave diggings in Southwest China have revealed fossilized remains of what may turn out to be a new human species, now referred to as the Red Deer Cave People. Skulls and other bone fragments have been dated to 14,300 and 11,500 years ago, with features distinct from modern man. This is an unusual finding, because human remains that recent would ordinarily be expected to resemble modern humans. However,  distinctive skull features include thick skulls, prominent orbital protrusions, jutting jaws and very large molar teeth. Their diet was rich in venison, hence the Red Deer Cave People name.
The Guardian features a wonderful lineup of the major human ancestors,beginning with Australopithecus afarensis, ‘the southern ape’, which lived between 3.8 and 2.9 million years ago. The Guardian has one of the best science search features I have ever seen on a newspaper site. You first click on the “News” tab, then the “Science” tab, then the “A-Z” tab at the end of the choices and voila–you have a huge menu before you that covers a broad array of scientific topics; for this particular story click on “anthropology” and you see the many links related to the subject, including the  story on the Red Deer Cave People. The entire Guardian is organized that way. It certainly gets my recommendation as the best way to organize an online news and information organization.

Red Deer Cave People (from The Guardian: possible human ancestor who lived 14,000 to 11, 500 years ago)

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In pursuit of Global Warming and Global Climate Change

Posted on August 9th, 2011 in Books,Climage Change,Energy,Environment,Evolution,Health,History,Science,Technology by Robert Miller

Fig. 1 Planet Earth (NASA)

Every educated person on the planet has heard about the threats to human existence imposed by Global Warming. Yet, few of us are knowledgeable enough to explain the basic mechanisms that determine our climate, especially when talking to those among whom are doubting members of the choir. Understanding the essential elements of Global Warming requires effort and an intellectual expenditure, but you can converse intelligently on the subject, while stopping short of explaining the situation on the basis of a thermodynamic theory of equilibrium. Besides, the earth’s climate has never truly been in any form of equilibrium–some positive or negative driving force or energy imbalance has always been trying to change our climate, though, until now, such changes have taken place over millenia, not over the two hundred plus years of the industrial revolution.  Our climate has always been changing, even though the time constants for change are way beyond a human lifetime, and lie properly scaled and recorded within the geological and paleoclimatological record, which gives up its secrets slowly. But once properly deciphered that record reveals a surprisingly coherent history for those willing to put the effort into interpreting the scrolls, or to be more accurate, deciphering the core drillings of oceans and glaciers. Of course, we don’t yet have a complete story. There are large gaps in our knowledge, but we know enough already to be mesmerized by our planetary history and the forces that have shaped our climate. And we should know enough to be alarmed and very wary about our future.

It is now clear that never before in our climate history have we witnessed the kind of experiment now underway–the forcing of our planet to go through something it has never experienced before–a sharp, man-made increase in atmospheric carbon dioxide that is now taking place and pushing us towards a climatological precipice that we might not be able to escape. But if we act quickly, this experiment is still under our control, depending on whether we can muster the political will to curb our use of fossil fuels and restore energy balance to keep the planet as it was, with atmospheric carbon dioxide at 350 parts per million (ppm) or less ; it is now at 387 ppm and rising at a rate of about 2 ppm per year. The alternative is that we run the risk of higher levels of carbon dioxide that will trigger the melting of Greenland and the polar ice caps and eventually raise our sea level by 270 feet! We are probably not at risk for a sea level increase of that magnitude during this century, but we do run the risk of having this kind of sea level rise take place, and once it starts, there will be nothing we can do to stop it. Not only will this massive ice melting proceed out of our control, it will cool the local regions where the melting takes place, impact our weather systems and change the driving forces for oceanic currents. The emergency we must address now has been created by the fact that the carbon dioxide we have put into the atmosphere has a very long half-life and its actions on our planet will be with us for a  very long time. Couple this reality to the fact that we are already seeing weather patterns that reflect Global Warming and you inescapably conclude that our short-term climate does not look good–it will inescapably be more violent. But, we can still do something for the long-term, by acting soon and now is not too early. There is little doubt that if we continue to burn fossil fuels through a business-as-usual mode, our planet will be markedly different and our planetary future will be seriously in doubt. In many ways, that’s the shock–not only that the climate is never in equilibrium, but that it is also super-sensitive to the very fuels we have chosen as our cheapest form of energy. For too long we have assumed constancy in our climate lives: that luxury has now gone, at least the assumption part of it.

The counter-intuitive interconnectedness of species

Posted on June 5th, 2010 in Climage Change,ecology,Environment,Evolution,Medicine,Nature,Science by Robert Miller

Red Knot Shorebird

Perhaps we need another century or two to understand the species of the world and their inter-dependencies before we make judgments about who should go and who should stay: say goodbye to one and you may have to do the same for a seemingly diverse group of animals for reasons that are highly counter-intuitive. It’s foolish of course to even suggest that we are in a position to make decisions about species survival, because we aren’t knowingly making those judgments, even though events, such as species extinction, are very likely occurring on a regular basis as a result of human interventionism. But, species extinctions are taking place without our knowledge of the cause or even, in most cases, an understanding of the species involved. We keep track of big animals, like lions, tigers, elephants and other large mammals and, though  the future for them is not looking particularly bright, we are completely ignorant about animals a step or two below on the evolutionary ladder–like the now extinct, Gastric-Brooding Frog. Who said goodbye to that species? But, here’s one to ponder for the short-term: are you kidding me?–shorebirds and horseshoe crabs? This survival dynamic may play itself out over the next few years.

The interconnectedness of nature almost dictates that you don’t lose single species, that in in losing one, some other species or fauna will also be put into harm’s way:  the loss of one species may precipitate the loss of one or more others, largely because we are unaware of the biological forces that unite them. I don’t know who else we lost or which other species might have been changed when the Gastric-Brooding Frog disappeared, but it didn’t disappear without impacting other species. Of that we can be certain. But, what connection for example does the continued vitality of the horseshoe crab, Limulus polyphemus, an ancient marine arthropod, have with survival of the Red Knot bird, a migratory shore bird that makes an annual stopover in the region in which the horseshoe crab breeds? The Limulus is virtually unchanged since it first appeared in the Paleozoic, 570-248 million years ago. Though most people have barely heard of the Limulus, anyone who studies vision is well versed with this species, as its compound eye was first used by H.K. Hartline to reveal fundamental mechanisms of visual physiology, for which he went on to win a Nobel Prize in 1967 for his pioneering work. Horseshoe crabs are abundant on the shoreline of Woods Hole Massachusetts, where Hartline did much of his early work. One of Hartline’s students, Robert Barlow, went on to show that the male Limulus uses its eyes to search aggressively for females and looks for the outlines of the carapace as a visual cue for finding a suitable female, at a time when the animals come into the shoreline for laying and fertilizing their eggs, an activity that usually takes place at night. But, who would ever have thought that the seasonal breeding of this ancient marine species, which takes place big time in Delaware Bay on the East coast, would have a dramatic impact on the survival of the Red Knot bird, a migratory shorebird that flies 20,000 miles each year, from South America to the Arctic, where it breeds, and then flies back again. Surely the biologists got this one wrong!

The Red Knot arrives in Delaware Bay just at the time the Limulus has come near the shore for breeding and egg laying. Eggs are laid by the female in the sand and then fertilized externally by the male or males that surround her. It is the nourishment derived from feeding on the newly released Limulus eggs that provides a critically needed source of food for the Red Knot to regain its stamina and prepare for resuming its long journey North.  Once the Red Knots arrive at the Delaware shore, they only have about two weeks to get sufficient nourishment, rebuild their wing muscles and store fat for the flight ahead to their Arctic breeding grounds, where they lay their own eggs and raise their young over the short summer of the region. If  insufficient Limulus eggs are available, the Red Knot does not seem to have a plan B and may be ill-equipped to finish the long journey to the Arctic. In some regions where Red Knots used to breed in the Arctic, they have not been seen in recent years and insufficient Limulus egg nourishment has been regarded as the main deficiency in their failed migratory outcome. In preparation for the long flight from South America (Tierra del Fuego, in Chile/Argentina) the bird’s digestive system shuts down, such that the intermediate stop, to feed on Limulus eggs, provides the bird with a very digestible meal, rich in proteins–apparently the ideal food for building up muscle and fat for an animal with a reduced capacity digestive system. Despite the aggressive feeding of the Red Knot on Limulus eggs, the horseshoe crab population in the region was stable into the 1990s, when fishing with Limulus bait became popular.

The shortage of Limulus eggs seems to reflect an overly aggressive harvesting of animals, particularly gravid females used by fisherman as bait for catching eels and conch (marine snails): this has led to a significant decline in the number of Limulus eggs laid on the shoreline, down to perhaps 2/3 of previous estimates and the magnitude of this decline has been implicated in the reduced numbers of Red Knot birds making it to their Arctic breeding grounds. Indeed, it was the alarmingly fast reduction in the Red Knot population, by about 70%, that led to the discovery of their dependence on Limulus eggs in Delaware Bay.  The decline in Limulus breeding and egg-laying seems to be the tipping point that could wipe out the Red Knot and could do so very quickly if a better balance isn’t restored.   There is now a two-year moratorium on using Limulus for fishing bait in the region and researchers are busy trying to find artificial bait substitutes that could be used in place of the real thing. An excellent video about this species interdependency was shown recently on PBS and can be seen here.

How long this interconnectedness between a marine animal that is roughly 350 million years old and a bird, whose evolutionary record goes back 150 million years, is not a matter that can be resolved through the fossil record. At some point, the Red Knot’s migratory flight to Delaware Bay was initiated to be well-timed to the breeding season of the Limulus.  This synchrony could be seriously interrupted further by global climate change which might affect one or the other of these tightly timed mechanisms. Some biologists believe the Red Knot could be extinct within five years. At some point, you reach a bird density wherein birds can’t find one another to mate.

Limulus polyphemus

The fishing industry is not the only survival challenge that Limulus faces. The blood of  Limulus has been used for many years because of its unusual properties. Limulus blood is blue because it uses a copper protein as an oxygen carrier. But, of more importance is the fact that Limulus blood clots whenever it comes into contact with endotoxins. Extracts of Limulus blood have been used for decades to test for bacterial contamination. One quart of Limulus blood is valued at about $15,000. Currently, the FDA insists that all intravenously administered drugs should be exposed to a Limulus blood amebocyte lysate as a test for endotoxins. This is a significant improvement over the prior process of injecting a rabbit with the substance and then waiting to see if the animal gets sick and develops a fever!  The discovery of Limulus amebocyte lysate also took place at Woods Hole, through the observations of scientist Fred Bang. This insight and its technological development has reduced the endotoxin analysis test from days to about 45 minutes. Instead of killing the horseshoe crabs and then bleeding them, the pharmaceutical industry harvests blood from live animals, who are then returned to their native habitat. Thus, some former fisherman, who used them for bait, now collect them for blood letting in a laboratory environment and then release them to the same location. Last year, 300,000 horseshoe crabs were bled and then released; about 13% do not survive this blood-letting procedure, which extracts about 2/3 of their blood.

The counter-intuitive interconnectedness of the Red Knot and the horseshoe crab could only be revealed by extensive field studies that involved capturing, tagging and measuring birds along the pathway of their extensive, almost incomprehensible, migratory flight pattern. These are dedicated scientists who share a passion for this bird and its preservation. Why a bird would exist under the harsh conditions of the Tierra del Fuego, near the Strait of Magellan, then fly to the even harsher climate of the Arctic for breeding and the early rearing of their young, before flying off again on another 10,000 mile trip, is well beyond our capacity to comprehend. Perhaps it got started before tectonic plates rearranged the land masses. The migratory pattern of North America by non-indigenous Homo sapiens was primarily East to West, which is a little easier to understand. In contrast to the rational, the Red Knot flight plan is not one that any of us would recommend to serve as the basis for a committed, routine lifestyle, unless it was one we recommended to our Republican friends. I can imagine Rush Limbaugh feeding on Limulus eggs in search of a new high. Let us hope that the Red Knot survives and the current iteration of the Republican Party goes the way of the Dodo bird as its major flight plan glides it  into extinction. There are many signs that such a glide pattern is already underway. We will undoubtedly hear more about each species in the coming years.

RFM

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