by D. Jones and A. C. LaMonica
Dr. Pennilyn (Penny) Higgins is a Research Associate in the Department of Earth and Environmental Sciences at the University of Rochester. Penny's research interests include: Stable isotope geochemistry of biogenic apatite and of carbonate minerals; annual-scale studies of ancient climate and dietary sources of fossil vertebrates using stable isotopes of tooth and bone apatite; atmospheric CO2 concentration and effects on plant metabolism through geologic time; uranium geochemistry and its relation to uranium ore deposition and fossil preservation; vertebrate taphonomy; and application of GIS to problems in paleontology.
Path of Reason: So what exactly does being a Paleontologist entail?
Penny Higgins: Paleontology is a lot of things. Most often, folks think of dinosaurs when they think of paleontology. Next most often, people think of Indiana Jones (which annoys paleontologists endlessly because Indiana Jones is an archaeologist, not a paleontologist). And then there’s the matter of Ross on “Friends.” Ugh.
Paleontology is in the midst of a revolutionary change in focus. Classical paleontology involves going out to the rock outcrop, finding fossils, carefully recovering the fossils, describing the fossils, and publishing what was learned. Paleontologists used the fossils, and the behavior of the extinct animals inferred from the fossils, to understand ancient environments and to put the rocks that the fossils came from into a general chronological order.
Today, a person can be a paleontologist and very rarely go out to the field to look for fossils. So much fossil material has been collected and not yet described that a paleontologist could make a career of publishing fossils that were collected and hidden away in a collection 100 years ago. Classical ‘descriptions’ of fossils are also becoming more and more rare. Journals prefer papers that use computer algorithms to calculate hypothetical evolutionary relationships among various fossil groups. Or, papers that apply engineering methods, like Finite Elemental Analysis, to understand biomechanical problems in extinct animals (like, did saber tooth cats slash or bite with their huge canines?).
Another common direction for paleontologists to go is toward the study of climate. This is, in part, because this is where the money is. This is where I have wound up. Lots of folks are studying the chemistry of fossils, and the rocks the fossils come from, to infer things like the mean annual temperature at the time the animal lived, how much rain fell at what time of the year, at what elevation were the animals living, or did the animals stay in one place year-round, or did they migrate? We know of several cataclysmic events that have occurred during Earth’s history. We can look at how climate changed during those events, and how the Earth’s biota responded, in order to better understand what may happen if Global Warming continues as it has.
POR: And how did you get started?
PH: This is a good question. It started when I realized I liked to draw horses, at the ripe old age of four. I had a strong bent for the sciences and for art and decided in high school that the best career for me would involve reconstructing dinosaurs from their bones. Ironically, I’ve never spent a single day doing paleontology on dinosaurs. I did my doctoral work in 60 million year old rocks in Wyoming. These rocks were deposited about five million years after the dinosaurs went extinct and were just teeming with mammal fossils. I discovered as a graduate student that I had as much, if not more, passion for geochemistry as I did for paleontology and started studying the isotope geochemistry of fossil mammals. I find it amusing that I have come full circle in a way. At four, I wanted to draw horses. Now, I do a lot of work with the geochemistry of teeth of modern and fossil horses. It’s all about the horses.
POR: What are your views on Intelligent Design?
PH: Intelligent Design is a slap in the face to real science. Proponents of ID start with their conclusions (that God created the world) and work backwards to try to prove it. Everything that IDists (and so-called creation scientists, too, for that matter) is based upon the assumption that God exists and he created the world like it is. Science intentionally leaves out any assumptions of the supernatural. For us, if we can’t find the answer to a problem, then we need to rephrase our question and ask again. We need, perhaps, to understand some more basic information before we can delve into the details. IDists and creation scientists essentially stop when the answer to a question seems unknowable. They claim that this unknowable answer is the work of God.
Now I should add that if God does exist and is capable of creating the world, then he could. He could have created the universe ten minutes ago and planted us all into it complete with memories and histories if he cared to. But to make such a claim is unscientific and it cannot be supported by scientific methods. Science offers plausible explanations for the origin of the universe, the origin of life, and the diversity of life on our planet that do not need to call on a supernatural being to make it happen. That is why Intelligent Design is not science, and why it should be kept out of biology classes in public schools.
POR: And how do you feel when people think evolution is fake?
PH: It frustrates me. It makes me want to cry. I wish I could mind-meld with people, ala Spock, to share my knowledge and understanding of biology, chemistry, and geology so they could see how foolish their thinking is. For the most part, I’ve found that folks that think evolution is bunk probably aren’t going to change their minds based upon anything I say. So I just try to be nice and offer my perspective if they care to hear it. That’s all I can do.
POR: What would you say are the most significant discoveries that support evolution (Ex. Transitional fossils.)?
PH: Of course, transitional fossils are among the best evidence that supports evolution. We have the classical horse evolution as one example. Other examples include transitional forms from land-dwelling dog-like carnivores to modern whales, transitional forms from hippopotamus-like herbivores to modern manatees, and the recently described transitional form between fish and amphibians (Tiktaalik). This isn’t the only evidence out there, this is just the neat evidence that hits the popular press. Transitional series between different species of diatoms (unicellular aquatic organisms) have been found, as well as transitional series between different species of mammal. These are continuous series, where the change from one species to the next is so gradual that it can’t really be marked.
Evidence to support evolution has come from several different sciences, as well. Biologists observe changes in gene frequency in populations of organisms due to environmental strain. Microbiologists observe new strains of unicellular organisms that arise because of their resistance to certain antibiotics. Molecular Biologists note that all organisms carry genetic information in the same molecule, RNA.
POR: It's apparent that many creationists are misinformed about evolution in general. There is plenty of creationist propaganda spreading false science amongst the masses to reassure them of such an understanding. How do we approach this issue and what can be done to ensure that people are properly educated about this matter?
PH: I wish I had a good answer for this. The most important thing that we, as scientists, can do is actually express our opinion. We need to be more willing to engage people who doubt evolution. The problem is twofold, however. 1) Academic-types are usually doing well to keep their research programs funded and their classes taught with a 50-hour work week. They seldom are willing to give up their free time to explain their views of science, especially knowing that such a discussion is often very like yelling at a brick wall. 2) Academic-types also have a tendency to forget how to speak plain English. We get so used to talking with other colleagues and students in the usual scientific jargon that it becomes impossible to even remember what Joe Public on the street may or may not know. We’re also used to dealing with people who will stop you and ask questions if they don’t understand you. Joe Public won’t do that because they either fear that you’ll think they’re stupid, or because they think you’re just being a jerk. (And frankly, sometimes scientists do this intentionally to get someone to go away.) Scientists get a bad rap for “sitting in our ivory towers” and looking down upon the general public. Really, the problem is a communications breakdown. More scientists need to be willing to engage the problem and more institutions need to value this work as much as they value teaching classes or writing grant proposals. Right now, defending science won’t get you tenure – writing grant proposals will.
POR: Can you explain Isotope Geochemistry and what it entails?
PH: There’s no quick way to explain isotope geochemistry, but here’s a quick primer on isotopes. I wrote this, in part, a few years ago when a high school student asked me essentially the same question:
You are probably already familiar with chemical elements: Carbon (C), Oxygen (O), Hydrogen (H), Nitrogen (N), and a zillion others. They make up molecules that make up all the materials around us: water (H2O), sugar (C6H12O6).
What you probably don’t know is that most elements come in different forms. There are three kinds of Carbon: Carbon-12, Carbon-13, and Carbon-14. These are called Isotopes. They occur naturally, and are present in specific, known abundances. About 98.9 % of all carbon in the world is Carbon-12. Most of the rest is Carbon-13. However, there is just the teensiest amount of Carbon-14 around as well. All these types of carbon act the same chemically and will be found in the same kinds of molecules. It is similar for all the other elements: 3 isotopes of Oxygen, 3 for Hydrogen, 2 for Nitrogen.
The only difference is their weight – Carbon-12 is the lightest and Carbon-14 is the heaviest.Because they have different weights, they behave just the tiniest bit different when chemical reactions occur. Because Carbon-14 is slightly heavier, it reacts slightly more slowly. The result is that as reactions occur, the different isotopes may be concentrated in new molecules formed during the reactions. This is called fractionation. We have a good sense of how this happens and can even calculate a number to predict what the fractionation is.
OK, I hope we’re doing well so far.
Now, there are two kinds of isotopes – stable and radioactive. Radioactive isotopes are unstable and will break down into smaller elements. Uranium is a good example of an element with radioactive isotopes. In fact, all isotopes of uranium are radioactive and decay (fall apart) until they turn into a stable isotope of Lead. Stable isotopes remain unchanged – they never decay.
All three isotopes of Oxygen (O-16, O-17, and O-18) are stable. Two of the three isotope of Hydrogen (H-1, and H-2 (or D)) are stable while the third (H-3 or T) is radioactive. Both isotopes of Nitrogen are stable (N-14 and N-15). Two isotopes of Carbon (C-12 and C-13) are stable, while C-14 is radioactive. Measurements of C-14 are used to date ancient fossils and artifacts (Carbon-dating). Carbon dating only works for materials 50000 years old or younger.
My research involves the use of stable isotopes from fossils and from rocks. I measure the ratio of Carbon-12 to Carbon-13 to make determinations about what kinds of plants were living at a particular time and or what plants an herbivorous animal chose to eat. I measure the ratio of Oxygen-16 to Oxygen-18 to determine climatic conditions. Here’s how it works (in a nutshell).
Different plants have different initial ratios of C-12 to C-13, and we know which plants have which value. For example, grasses in a desert have a typical ratio (called d13C “delta 13-C”) of –14‰ (said “14 per mil”); deep rainforest plants have a d13C value of –30‰. This ratio is reflected in tooth enamel of fossil mammals, organic carbon in rock, and in carbonate nodules found in rocks that formed as part of an ancient soil.
Variation in oxygen isotopes is mostly dictated by climatic variables such as temperature, humidity, and precipitation. d18O (delta 18-O) values of surface water go up (become more positive) when temperatures are warm. d18O values go down when temperatures are cool. But just to make things more difficult, d18O will also go down if temperatures are above 20C (about 68F) and it rains a lot. So from this we can get a general idea of climate – how warm it was and when (and whether) it rained. Elevation also has an effect on oxygen isotopes.
POR: Also, what is carbon dating and how accurate do you feel it is?
PH: As I mentioned above, carbon dating is great when you deal with relatively young materials (less than 50,000 years). Carbon dating is also difficult to use for really young things because all that nuclear testing that was done in the 50’s added lots of extra C-14 to the atmosphere.
POR: Are their any other ways to date fossils?
PH: There are numerous other ways to date fossils. Several other radiometric techniques exist, like K/Ar dating, Ar/Ar dating, U/Pb dating, Pb/Pb dating, and Nd dating. In these cases, you are generally dating the rock in which the fossil was found and not the fossil directly. Other non-radiometric techniques also exist, like fission-track or thermoluminescence. Techniques like paleomagnetism or dating according to what fossils are present (biostratigraphy) can also be used. Creationists like to argue that these last techniques are circular, but they fail to understand that the magnetic and biostratigraphic time scales are calibrated using radiometric or other chemical methods.
POR: What are you currently working on? What is your current focus in your field of study?
PH: I do a little of everything. My current projects in paleontology/geochemistry (some of which are collaborative with other scientists and some are on my own):
A) Diets and tooth growth in extinct South American hoofed mammals. These huge, rhino-sized, mammals have no modern relatives. They are fascinating because in many cases their teeth grew continuously. I want to know how fast the teeth grew and what they were eating that necessitated having ever-growing teeth.
B) Climate change and uplift of the Andes Mountains in the last 25 million years. The Andes rose over three kilometers during this span of time. We can use geochemistry to constrain the timing of this uplift as well as to understand the effect that the new mountains had on the climate of South America.
C) Climate change at the Paleocene/Eocene boundary about 55 million years ago. This boundary is characterized by a huge global warming event and associated turnover of animal and plant species. I’m going to use isotopes from fossil freshwater clam and snail shells to determine what effect this warming had on the seasonal variability of precipitation and humidity in Wyoming.
D) The nature of climate change since the last glacial maximum ~15000 years ago. We are using isotopes from horse and bison teeth to look at climate changes over the last few thousand years.
E) The geochemistry of uranium ore deposition and how this affects the preservation of vertebrate fossils. Who knew there was a relationship?! But this is important, as many of the best fossil localities in the Rocky Mountains are in basins also known for uranium ore deposits.
And then there are the other things I do, like:
F) I’m preparing a tutorial and implementation guide for using a computer program specifically designed for data from stable isotopes. I’m teaching a one-day class on this in about two weeks.
G) I’ve developed a new method for analyzing the hydrogen isotopes of water that I need to publish.
H) And, of course, anything I can do to promote science and debunk pseudoscience like intelligent design.
And in my spare time:
I) I have a 3-year old son who likes trains.
J) I have a much older husband that likes music.
K) My husband and I have a collection of over 600 antique or archaic cameras.
L) I love to garden and am an officer in the local garden club.
:END:
No comments:
Post a Comment