Subject: Speculation on the Causes of Cancers and Disease

Phil Colla (
Tue, 17 Feb 1998 10:43:37 -0800

>I would like to find some
>information on thes beuatiful mammals dieing of cancer.  I want to know what
>the effect will be on the human race when these mysterious creatures are no
>longer with use due to no fault of their own.  Also, I was taught that
>along with dolphins could not get cancer.  But here they are beaching
>themselves, and full of cancer.  Why? And what could be the effect?  Thanks.

Yours is a broad question!  I think that very few animals are immune to
Cancers are such a broad family of disease that they can afflict almost 
any animal, certainly the higher-ordered animals like vertebrates.
the elasmobranchs (sharks and rays) seem to be robustly immune to cancers,
is one reason people want shark-cartilige powders and the like as health
supplements, although there is no evidence to suggest that such  chemicals
aid human health.

It is very possible that cetaceans are contracting cancer due to toxins in
environment, either naturally occurring (like some planktons) or human-induced
(like pollution).  A good number of marine mammal researchers are studying
issues, and publish their findings in scientific journals.  Occasionally,
finding are noticed by the mainstream press and the world at large becomes
aware of
them.  The wide range of expertise required to study these disease and
factors is so large that no one person can be expert on the issue.  I
myself study
just the behavior of one type of whale, and no little about diseases among
marine mammals.

It is also possible that the cancers and disease that we observe in marine
are _natural_, and have been happening for ages, and we are just noticing
them now
as we become more "environmentally sensitive".  I don't think this is the
but it is possible.

It is most likely a mix of natural- and man-made factors that is
responsible for
the marine mammal diseases you mention.

As to what marine mammals cancer and disease bodes for mankind, that is a
question.  It is probably conservative to say that we all recognize the
ways in which humanity of harming the earth.  What is more contentious is the
question of what are we going to do about it.

Phil Colla

Phil Colla,
Humpback Whales: