The Endangered Species Act is based on outdated science

We have reported to our readers many times about the changes in scientific opinion regarding invasion biology in the past fifty years, since the inception of the theories that originally supported that discipline.  Now we see an acknowledgement of the changed scientific viewpoint in a critique of the Endangered Species Act by the legal profession.

Holly Doremus is Professor of Law at Boalt Law School at the University of California, Berkeley.  Her critique of the Endangered Species Act (ESA) was published by the Journal of Law & Policy in 2010.  She previews her theme in her introduction:

“I am interested in why the ESA came to assume an unrealistically static vision of nature.  First, the Act’s static structure is typical of law in general, which has traditionally embodied the human search for stability.  Second, the Act is inevitably, a product of the political times in which it was drafted and of a rapid and chaotic legislative process, which did not encourage thoughtful examination of the complex contours of the conservation problem.  Third, it followed in part from incorrect but widely shared assumptions about the nature of the problem and potential solutions.  Fourth, scientific understanding was itself in transition as the law was being crafted, moving from a focus on the tendency of ecological systems to approach equilibrium to one on the ongoing dynamics of many systems.” (1)

We will focus on the fourth issue, i.e., how the ESA is in conflict with the reality of constantly changing ecosystems. 

A Static Vision of Nature

The ESA is based on assumptions about nature that were the conventional wisdom at the time the law was passed in 1973:

  • Evolution was considered an historical process that was no longer actively changing plant and animal species.  Theoretically evolution does not end, but at the time the ESA was passed in 1973, it was not believed to occur within a time frame that would be observable by man.  Plant and animal species were therefore viewed as being distinct and unchanging.
  • This view of evolution was consistent with the prevailing public opinion in the United States, which does not believe in evolution.  Many Americans believe that species have not changed since they were created by God.
  • Nature was perceived as reaching an “equilibrium state” that was stable over long periods of time.
  • Early conservation efforts were therefore based on the assumption that once achieved, an equilibrium state could be sustained if left undisturbed in nature preserves.

    Darwin's finches are an example of rapid evolution
    Darwin’s finches are an example of rapid evolution

We now know that these assumptions were mistaken.  Evolution can occur very rapidly, particularly amongst plants and animals with short life spans and frequent generations.   And ecosystems are constantly changing, particularly at a time of a rapidly changing climate and associated environmental conditions such as atmospheric conditions. 

Professor Doremus tells us that ecological scientists played no role in the writing of the ESA and took little notice of the law when it was passed.  The press also ignored the new law, which may have been a factor in its being unnoticed by the scientists who may have been in a position to raise the questions that should have been asked.  “It seems that conservation scientists, like the general-interest press, and most legislators, did not consider the ESA groundbreaking, or even particularly important.” (1) In any case, the problems that have arisen in the implementation of the law were not foreseen by the politicians who passed it, nearly unanimously in 1973.

How does the ESA define “species?”

As its name implies, the heart of the law is how “species” are defined.  In fact, if the law had stopped at providing legal protection for “species,” we would not be experiencing nearly as much difficulty with the implementation of the law.  Unfortunately, the ESA’s “…definition of ‘species’ [is] broad, but not a model of clarity, ‘The term “species” includes any subspecies of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish or wildlife which interbreeds when mature.”  (1)

Splitting species into sub-species and “distinct population segments” has proved very problematic because taxonomy (the classification of organisms) has always been inherently subjective and will probably continue to be.  The taxonomic system that was popular at the time the ESA was passed was Mayr’s biological species concept which identifies as a species any group that interbreeds within the group but not with outsiders.  This definition is not useful for a species that hybridizes freely, such as the manzanitas of which six species have been designated as endangered.  Professor Doremus tells us that US Fish & Wildlife Service now evaluates the legal consequences of hybridization on a case-by-case basis. 

Since the ESA was passed, many competing definitions of “species” have been proposed by scientistsThere were 22 different definitions of species in the modern literature as recently as ten years ago.  These competing definitions reflect disagreement about appropriate criteria for identifying species—morphology, interbreeding, or genetic divergence, as well as the degree of difference needed to define the boundary between species.   We see these scientific controversies played out repeatedly in the law suits that are interpreting the ESA. 

The identification of “distinct population segments” amongst vertebrates has proved to be even more problematic.  Legal challenges to the determination of distinct population segments have reversed the rulings of the US Fish & Wildlife Service for many species that were considered genetically identical such as the sage grouse (eastern vs, western?) and the Preble’s meadow jumping mouse (found in different meadows in the Rocky Mountains).  In some cases, these rulings were reversed several times, and perhaps will be again!  These reversals reflect the ambiguity of the law, as well as the science of taxonomy.  The fact that the ESA specifically allows “citizen suits” has pushed the regulating agencies to implement the law more aggressively than  politics alone would have predicted.

Species can and do move

In addition to considering species immutable and unchanging, the ESA also takes a static view of where they live.  The concept of “distinct population segments” depends somewhat on the assumption that species of animals don’t radically alter their ranges in the short-term.  The assumption is also consistent with the underlying conservation policies that tend to preserve specific places in order to protect rare species within those places.

We now understand that some ecosystems are internally dynamic.  We recently told our readers of the need for the sand dunes near Antioch, California to move freely in the wind to sustain that fragile ecosystem.  Professor Doremus also tells us about the constantly changing courses of braided rivers in Nebraska that are essential to the sustainability of that unique ecosystem. 

Platte River in Nebraska is a braided river.  Creative Commons
Platte River in Nebraska is a braided river. Creative Commons

In a rapidly changing climate, the preservation of a species may require changing ranges.  If the climate becomes too cold, too hot, too wet, or too dry for a species of plant or animal, its immediate survival may require that it move to higher or lower altitudes or latitudes.  Moving may be a more effective strategy than the adaptation that may be slower than necessary to survive.  Freezing species into their historic ranges does not ensure their survival at a time of rapidly changing climate.  In some cases, a species has become plentiful in the new territory it has freely chosen to inhabit and simultaneously rare in its historic range where it has been designated as an endangered “distinct population.”  Draconian measures have been taken to restore a species in its historic range, where it is no longer adapted to current conditions.  

We leave you with Professor Doremus’ observation about the ESA:  “The ESA’s static view of species, landscapes, and conservation obligations, while entirely understandable, has become a hindrance to effective conservation.  The ESA’s lofty goals of conserving species and the ecosystems upon which they depend cannot be achieved without a more realistic vision of the dynamic qualities of nature and the ability to respond to the changes that are inevitable in dynamic systems.”


(1)    Holly Doremus, “The Endangered Species Act:  Static Law Meets Dynamic World,” Journal of Law & Policy, Vol. 32: 175-235, 2010.