Send your girls careening toward a career in hard sciences with HMNS summer camps

Let your young lady soar with HMNS’ Careers in Science program, designed to encourage girls to explore, well, careers in science!

Girl Scouts - Careers In Science
The Careers in Science curriculum offers three classes: Paleontology, Biology and Chemistry.

Careers In Science: Paleontology

At the Paleontology class, participants meet off-site and dig into history to uncover 45 million-year-old fossils from locations on the banks of the Brazos River and at a park teeming with petrified wood. Each participant keeps the fossils she finds!

Girl Scouts - Careers In Science
In Biology class, participants go behind the scenes of the Cockrell Butterfly Center to learn where our butterflies are sourced, how the plants are grown and even how our waterfall works. They’ll also interact with live insects and learn just what makes our “containment room” so important.

Girl Scouts - Careers In Science
Finally, Chemistry class teaches participants about everyday chemical reactions through hands-on experiments, including creating chemical temperature changes and understanding the role chemical reactions play in cooking.

Siblings at least 10 years of age can also participate in class with the purchase of a ticket, and each class ticket allows one adult to accompany each child.

Email scouts@hmns.org or check out the website for more information. You can also sign up for our monthly Scouts newsletter and be the first to learn about upcoming classes!

The Eyes Have It: Evolutionary Development and DNA

Today’s guest blogger is Neal Immega. He has a Ph.D. in Paleontology and is a Master Docent here at HMNS. In his post below – originally printed in the Museum’s volunteer newsletter – Neal discusses Evolution Development and DNA.

Popular media crime shows, like CSI: Crime Scene Investigation, show amazing applications of DNA technology. For example, a person can be traced to a specific location by means of cells he left on a door knob.

A new science called “Evo-Devo,” shorthand for Evolutionary Development, can tell us even more amazing information. Evo-Devo techniques probe deeply into the structures of DNA to look at how DNA actually codes for the growth of body parts, telling us more about the animal kingdom than we ever dreamed possible. It shows genetic similarities between very different organisms and lets us understand how two organisms, like mice and men, can have DNA that is 85% similar and, yet, code for very different organisms.

We all know the basics of DNA molecules, where the genetic code is stored by a very long sequence of four proteins strung together in various arrangements. That is the easy part! What we need to
worry about is how these genes blueprint a living being. Geneticists, like Sean Carroll (whose popular books are listed in the references box), have discovered that the DNA code is made up of some large master programs that control things, such as eyes, and lots of very small programs (they call them switches) that control what kind of eye will be displayed.

Normal Fruit Fly
Image courtesy of The Exploratorium

Let’s confine ourselves to understanding and experimenting on simple life forms, such as fruit flies. To figure out which specific piece of DNA causes some feature to appear in a developing embryo, geneticists experimentally inactivate a segment of DNA, transplant the complete strand (including the inactivated segment) back into the egg, fertilize that egg, and then see what turns up missing. If that missing part is not vital for survival, the egg might even grow into an adult fly. Compare the drawings of a normal fly with the one below it where the master program for eyes has been deleted.

Eyeless Fruit Fly 
Image courtesy of The Exploratorium

Such experiments have found that the master program for making eyes can cause an eye to grow on a fly’s leg, body, antenna, or inside the body, depending on where it is placed on the DNA strand. Check out the drawing showing the results of moving the master program for legs to the site of the antenna. Note that the extra legs are fully formed but lack the neuron connections to the brain and so are not functional. (In the references box is a link to an electron microscope image of a real fruit fly that shows a mutation in which eyes replace antennae.)

Various mollusks (like clams, snails, and octopuses) grow eyes that vary in complexity from very simple sensitive pits to complex eyes that would compete well with human eyes. The EXACT SAME eye master program from a fruit fly can replace the eye master program for a squid, and it will grow a perfectly functional squid eye. You might be tempted to say that fruit flies and squids are cousins.

Fruit fly with extra legs
replacing the antennae 
Image courtesy of The Exploratorium

That is an amazing statement, but to take it even further, the same experiment with a mouse eye master program will grow fly eyes on flies and squid eyes on squids. They only differ by the small switch segments. These experiments establish a link between vertebrates and invertebrates that paleontologists are unlikely to find in the rock record. This also helps explain the amazing degree of structural similarity between mice and men—although many of the master programs are similar, the really critical parts of the DNA are the small switches that control the details.

Mollusks have just one master program that is controlled by different switches. Pectens, for example, have the most complex vision arrangement of any animal with three different types of eyes on its body. The DNA can be experimentally adjusted to grow any of these eyes anywhere on the body. Random mutations could thus cause novel arrangements, and survival would judge their fitness—evolution in action.

The switch concept explains how mice, chimps, and humans can have a similar number of genes. The switches control the result of the master programs. You can pick up any modern textbook and read that men and chimps have nearly identical genes. It is the switches that make us different and that provide the evolutionary means for dramatic changes, good and bad.

The fossil record is full of cases where a dramatic new species just appears. Paleontologists have often wondered if this was caused by a missing rock interval, by migration, or by rapid evolution. The concept of rapid evolution has often been discounted because it seemed to violate the incremental nature of evolution. We now can see how rapid evolution may just be a single point mutation in a switch. There are numerous biological examples where altering one protein is lethal, as in Tay-Sachs disease, or altering another might bear strongly on survival, as in changing
the color of hair from white to black.

Geneticists can now explain things in a way that profoundly affects how we think about evolution. Biologists and paleontologists have always wondered if evolution had to generate complex structures like eyes from scratch for each phylum. The reuse of master programs from very simple life forms through complex ones means that evolution can build on what went on
before. Critics of evolution often claim that eyes are too complex to have evolved. (The “half-an-eye-is-nogood” argument is derived from the first sentence of the Darwin quote in the box below.) Now, with Evo-Devo tools, we can see commonalities between the genetics of simple life forms and complex life forms– between clams and people.

The possibilities just became more complex.

REFERENCES:
Wyoming Dinosaur Center: http://www.wyodino.org/

Sean B. Carroll:
Endless Forms Most Beautiful: The New Science of Evo-Devo, (paperback) 2006
The Making of the Fittest: DNA and the Ultimate Forensic Record of Evolution,
(paperback) 2007
Remarkable Creatures: Epic Adventures in the Search for the Origins of Species, 2009

Lynn Helena Caporale:
Darwin in the Genome: Molecular Strategies in Biological Evolution, 2002

SEM (scanning electron microscope) photograph of eyes replacing antenna in a fruit fly by Naoum
Salame. http://1tv4.sl.pt

Fly Eye Genetics:
http://www.pbs.org/wgbh/evolution/library/04/4/text_pop/l_044_01.html
Renowned scientist Dr. Walter Gehring discusses master control genes and the evolution 
of the eye.

Darwin, 1859, The Origin of Species, http://darwin-online.org.uk/contents.html. In most editions, the quote appears on pp143-4.

The gift that keeps on giving: Darwin and the Origin of Species

In conjunction with Darwin2009 Houston, a year-long celebration of Darwin’s 200th birthday and 150th anniversary of the publication of “On the Origin of Species,” HMNS will host a series of events exploring the contributions of this famous scientist.

Today’s guest blogger is Francisco J. Ayala, who shares some his findings here prior to his Feb. 24 lecture at the Museum, on “Darwin’s Gift to Science and Religion,” a part of HMNS’ Distinguished Lecture series.

The Origin of Species #1
Creative Commons License photo credit: gds

Darwin occupies an exalted place in the history of Western thought, deservedly receiving credit for the theory of evolution. In The Origin of Species, he laid out the evidence demonstrating the evolution of organisms.  However, Darwin accomplished something much more important than demonstrating evolution. Indeed, accumulating evidence for common descent with diversification may very well have been a subsidiary objective of Darwin’s masterpiece.  Darwin’s Origin of Species is, first and foremost, a sustained argument to solve the problem of how to account scientifically for the design of organisms. Darwin seeks to explain the design of organisms, their complexity, diversity, and marvelous contrivances as the result of natural processes. Darwin brings about the evidence for evolution because evolution is a necessary consequence of his theory of design.

The advances of physical science brought about by the Copernican Revolution had driven mankind’s conception of the universe to a split-personality state of affairs, which persisted well into the mid-nineteenth century.  Scientific explanations, derived from natural laws, dominated the world of nonliving matter, on the Earth as well as in the heavens.  Supernatural explanations, which depended on the unfathomable deeds of the Creator, were accepted as explanations of the origin and configuration of living creatures. Authors, such as William Paley in his Natural Theology of 1802, had developed the “argument from design,” the notion that the complex design of organisms could not have come about by chance, or by the mechanical laws of physics, chemistry, and astronomy, but was rather accomplished by an Omnipotent Deity, just as the complexity of a watch, designed to tell time, was accomplished by an intelligent watchmaker.

It was Darwin’s genius to resolve this conceptual schizophrenia.  Darwin completed the Copernican Revolution by drawing out for biology the notion of nature as a lawful system of matter in motion that human reason can explain without recourse to supernatural agencies. Darwin’s greatest accomplishment was to show that the complex organization and functionality of living beings can be explained as the result of a natural process—natural selection—without any need to resort to a Creator or other external agent.  The origin and adaptations of organisms in their profusion and wondrous variations were thus brought into the realm of science.

crab on the rocks
Creative Commons License photo credit: angela7dreams

Evolution can be seen as a two-step process. First, hereditary variation arises by mutation; second, selection occurs by which useful variations increase in frequency and those that are less useful or injurious are eliminated over the generations. “Useful” and “injurious” are terms used by Darwin in his definition of natural selection. The significant point is that individuals having useful variations “would have the best chance of surviving and procreating their kind.” As a consequence, useful variations increase in frequency over the generations, at the expense of those that are less useful or injurious.

Natural selection is much more than a “purifying” process, for it is able to generate novelty by increasing the probability of otherwise extremely improbable genetic combinations.  Natural selection in combination with mutation becomes, in this respect, a creative process.  Moreover, it is a process that has been occurring for many millions of years, in many different evolutionary lineages and a multitude of species, each consisting of a large number of individuals. Evolution by mutation and natural selection has produced the enormous diversity of the living world with its wondrous adaptations.

Francisco J. Ayala is a noted biologist and philosopher at the University of California at Irvine’s Department of Ecology and Evolutionary Biology. Don’t miss his lecture on Feb. 24 - or any of the other Darwin2009 events planned at HMNS this year.

My love affair with the tropics (how and why I became a biologist)

 Our fearless leader
Dr. Larry Gilbert

My introduction to the tropics was in the summer of 1983, when I lucked into accompanying Dr. Larry Gilbert (UT Zoology) and his students on a field course to Corcovado National Park in Costa Rica.  Not being a student at the time (I’d gotten a BA in linguistics a couple years before but was working as a secretary on the UT campus), but having some proficiency in Spanish, I was hired by Dr. Gilbert as his assistant and translator since his regular teaching assistant was off making a film in New Guinea. 

After several weeks in Patterson Hall on the UT campus, translating documents and readying equipment, we left for Costa Rica, flying into the capitol, San Jose.  Here our party (5 graduate students plus Dr. Gilbert – Larry to his students – and myself) spent a couple of days at the “Costa Rica Inn” – a rambling one-story labyrinth of a hotel near the downtown area.  San Jose is a typical Central American city, with lots of traffic and pollution, no interesting architecture to speak of…but great ice cream and plenty of activity – and in those days, very safe at all hours.  We visited the Natural History Museum and the local university, picked up some supplies (foam mattresses and rum are what I remember!), and made our flight arrangements.  We were flying in to the park in two 5-seater Cessnas; there was no other access to the remote field site location. 

View of the Corcovado canopy from the plane.
Photo by Dr. Larry Gilbert.

The day arrived and we boarded the tiny planes.  I was quite nervous as I had never flown in such a small plane before, and the pilot warned us that it might be a bumpy ride due to rising air currents as we crossed the mountains.  And Larry joked about the two wrecked planes that decorated the end of the airstrip in the park… 

The flight took about an hour, and it was indeed turbulent.  Finally we flew out over the Osa Peninsula and saw nothing but forest below us, and then the Pacific Ocean beyond. We suddenly turned at right angles to the coastline to land at a tiny airstrip cleared in the rainforest, ending at the beach…and there, indeed, were the two wrecks.  Welcome to Sirena Station of Corcovado National Park!

We pitched tents in the clearing/horse pasture behind the rustic park station building; this would be our home for the next six weeks.  The students included Darlyne, studying heliconius butterflies; Kirk, studying the fish communities in freshwater streams; Jamie, studying howler monkeys, and Peggy and John, new students who had not yet decided on projects.  Two senior students, Peng Chai and Sue Boinski, were already in the park.  Peng was studying bird predation on butterflies.  “Bo” as she was called, was the equivalent of a mountain man, in my somewhat awed view.  She had spent the past several years following troupes of squirrel monkeys to learn about their behavior and mating habits, sometimes staying in the park for over a year at a stretch. In the course of her wanderings she had dodged fer-de-lance and bushmaster snakes, and had some (very shaky) video footage of a pair of jaguars lazily playing together, oblivious of their nervous human watcher. 

Fruits of the
Corcovado rainforest.
Photo by Dr. Larry Gilbert.

The Sirena station was a bustling place.  Since in those days (before the gold miner crisis of 1985) it served as the park headquarters, it was the central point in Corcovado for communications and supplies, which were all brought in by plane.  The park director was stationed here, along with about 5-6 park guards.  Other park guards travelling by horseback from the outlying stations came in to pick up their allotment of supplies, or to rotate out for a week’s holiday.  The radio crackled all day long:  “Sierra Papa Norte Dos a Sierra Papa Norte” (National Park Service station 2 to headquarters).  I learned all sorts of things in radio lingo – “Cambio” meant over, “Dos” meant good, “Dos y medio” was so-so, “Tres” meant bad, “un 22” was a telephone call, “10” was crazy, etc. 

The station in those days was rustic.  Electricity was provided by generator only at lunchtime and for a couple hours in the evening.  Running water was ingeniously piped in from a nearby stream.  Course participants and park guards all ate together in a little open-sided building:  generous portions of rice and beans, smaller portions of meat and vegetables, inventive desserts, and drinks made from fresh tropical fruits, all deliciously prepared by Maria, the feisty and attractive cook.

Buttress of a tropical giant.
Photo by Dr. Larry Gilbert.

The first few days Larry led his students and me on long, sometimes wild walks through the forest – up over the steep knife-edged ridges, crashing down through stream beds, slogging along the beach or sweltering through open areas.  What an amazing place!  I was in love with the forest from the moment I saw it.  So many plants – so many insects, birds, monkeys, frogs, snakes, etc.  But especially plants.  It was like being in the most amazing botanical garden.  Here things I’d only seen as houseplants grew rampantly everywhere.  Ferns were not just ferns but trees.  And trees, with their huge buttresses as big around as a house, towered into the canopy.

Squirrel Monkies are common
near Sirena

After a week or so of our introductory walks, the students settled down to their research projects.  Since I wasn’t a student and didn’t have my own project, I helped some of the others where I could.  I soon was spending most of my time with Kirk, helping him census the fish in the many small streams that cut across the peninsula – streams so clear and clean that we drank out of them.  I learned a lot about fish that summer!  At night, we all sat in the little screened porch behind the radio room, burning candles and mosquito coils while we read or wrote up our field notes, or listened to one of the students give a status report on his or her project.  Larry often regaled us with funny stories of his past students…considerably embellished over the years, I am sure!

 Tropical leaf-footed bug

All too soon the summer came to an end, and we had to leave the park and head back to Texas to begin the new semester.  We packed the tents and our supplies into coolers to keep out the mildew.  Said our goodbyes to the park guards and to Maria.  Cleaned up the area we had taken over as our evening “lab.”  While we waited for the planes to arrive I took a last walk up the Claro trail to a ridge where, sitting on the buttress root of a huge strangler fig, I could see over the forest and out to sea.  What an adventure it had been!  What a lot of amazing biology I had learned!  Nostalgia for the place swept over me – but I heard the drone of the plane and had to rush back to camp.  We boarded the Cessna, and as it rumbled down the bumpy airstrip and began to lift into the air, I thought – if the plane crashes on the way back, I will die happy.  I have just spent the most amazing summer of my life.

I ended up becoming one of Larry’s students and spending several more summers in the park and elsewhere in the tropics.  However, that first experience stays with me as one of the real highlights of my existence on this earth. 

 Ornate flower of a tropical passionvine
 Red-eyed treefrogs.