Genes are not these passive little things that we just inherit from our parents.  They’re active.  They’re a symphony throughout our lives.  A symphony needs a conductor and hormones are the conductors.  Hormones signals are generated by a wide array of factors.  Hormone signals guide the turning on and turning off of genes.  It’s called gene expression.  That’s central to life. 

It turns out that hormones basic function is to control the turning on and turning off of genes.  Genes are active throughout our lives.  They’re crucial in guiding development.  They have to be turned on or turned off at the right time so the right protein is present.  If this trigger is not there or another is at the wrong time, you may not have the right number of fingers.  Your brain may wind up being wired inappropriately. 

Genes are not these passive little things that we just inherit from our parents.  They’re active.  They’re a symphony throughout our lives.  A symphony needs a conductor and hormones are the conductors.  Hormones signals are generated by a wide array of factors.  Hormone signals guide the turning on and turning off of genes.  It’s called gene expression.  That’s central to life.  We’ve discovered that some contaminants, at extremely low levels are capable of interfering with the signals that are turning genes on and off.  They do that by mimicking hormones or by blocking hormones.  In one way or another some contaminants amplify or diminish the signals specific hormones should be sending. They interfere with the degree and timing of gene expression. Some aren’t being turned on or the trigger is happening at the wrong time. Some may be silenced permanently. When this happens there are problems.

It’s so beautiful to see what nature has created.  But it has to work in the right way.  Imagine Beethoven’s Fifth.  Imagine it’s going along, dunt-dunt-dunt, and then the note doesn’t hit.  That’s jarring to those of us know how is should sound.  It’s devastating if the gene that’s needed at that precise moment doesn’t fire in the development of an organism. It’s devastating.

One frog story is about what scientists call “intersex” or “hermapherdism” in frogs where you have frogs that have mixed gonads where they’ve got both testes and ovaries.  It’s not normal in people, it’s not normal in frogs.  That is clearly due to, at least in the cases that have been well studied, is due to exposure to pesticides that are turning on a gene that speeds the conversion of testosterone to estrogen.  Gene products often capitalize other chemical reactions in the body.  So in this case you’ve got a gene that’s turned on and produces an enzyme called Aromatase.  Aromatase’s job in the body, at least one of the jobs, is to take testosterone and make it into estrogen.  Well that happens too rapidly in development in these frogs.  It means that the frogs are de-masculinized and this intersex condition is created.  So that’s one very well studied phenomena right now. 

In the late 90's there was another frog issue that burst upon the public scene when a group of school kids in Minnesota were out on a field trip and they discovered a pond full of deformed frogs with multiple legs and eyes in the wrong places in the body.  It grabbed a huge amount of attention.  A scientific debate unfolded, it erupted over that issue that took almost a decade to finally reach some closure on it.  Not surprisingly.  It’s complicated.  It’s not just chemicals.  It’s not just natural.  It’s a combination of processes, at least the picture right now is that several things have taken place as a result of human changes, human impacts on the environment that lead to these local eruptions of frog deformities.  The current picture on that now is that the actual deformity, a deformity in those frogs is being caused when a parasite, a natural parasite of the frog creates a cyst in the tadpole, near the developing limb, the leg of the frog.  They’re forced to develop right in the early stages of development, this parasite encysts itself, encapsulates itself and causes a physical irritation to the limb bud that’s developing.  Then when the frog changes into adulthood it metamorphosis.  That cyst and the irritation causes the bizarre deformities.  Some people reacted to that and said oh it’s natural.  Well, there are two things that are happening at the same time.  First, all the agricultural fertilizers that are being used around those ponds are making the environment much more favorable for the parasite.  Now it’s a complicated story.  It turns out that this parasite lives part of its lifetime in snails and part of its lifetime in frogs.  And the effect of the agricultural chemicals is to make the pond more conducive to the snails.  The more snails there are the more parasites there are the worse it is for the frogs.  So that’s part of it. 

The other part is that the pesticides that are in those same ponds along with the fertilizers are dampening the frogs ability to resist the parasites.  So their immune system is being impaired.  So here you’ve got this complex system with natural snail, natural parasite, natural frog, interactions that may have produced very low rates of frog deformities in the past.  All the sudden with the dumping of large numbers of chemicals; fertilizers, pesticides into it, you wind up with more parasites and a frog that is less capable of resisting the parasites affect.  For a while this science unfolded as oh it’s got to be the parasites or its got to be the pesticides.  Well now we know it’s both.  And that’s a classic outcome of this sort of work.  It’s not one or the other.  If we devolve into doing is arguing, oh it has to be this, it has to be my idea, we miss this bigger picture which is it’s how the system is working.  And humans, human activities often cutting into a system from multiple directions, having these profound affects like eruptions of frog deformities.