Travel Reference
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waters, at a site called Dinah's Beach in eastern Papua New Guinea. They
were as dazzled by their experience as I was by Lembeh. They called their
adventure “muck diving,” after the mud and detritus that characterizes such
sites. The name, if you will forgive me, has stuck.
Because so much of the evolution of life has taken place in the oceans, it is
not surprising that life's diversity confronts us more vividly below the waves
than above them. In a walk through the rainforest that shrouds the moun-
tains near the Lembeh strait you will see a wide variety of fl owering plants
and many vertebrate animals. You will also encounter many insects and
other arthropods such as giant centipedes. But if you swim around Lembeh's
sandy bottom you will immediately fi nd large and colorful animals from a
far wider collection of phyla, ranging from the most primitive sponges to
the most complex mollusks and vertebrates. The sea is an evolutionary time
machine.
Muck-diving through evolutionary time
What would we have seen if we had been able to go muck-diving in earlier
times? If we could travel back far enough, we would fi nd a very dif erent
world.
The Solar System, including the Earth, formed four and a half billion
years ago, but we can only trace the history of the Earth's crust back four
billion years. Before that time our newly formed planet was being pounded
mercilessly by massive objects from outer space, so that its crust was melt-
ing and solidifying repeatedly. After the crust fi nally cooled and was stable
enough to accumulate oceans and support life, living organisms appeared
surprisingly quickly, probably around three and a half billion years ago. Yet,
for the fi rst three billion of those years, any time-traveling muck-divers that
ventured from the lifeless land into the oceans would have swum over a
seemingly dull and uniform sea bottom. The divers would have seen feature-
less mud fl ats dotted with layered concretions of bacteria and algae called
stromatolites.
 
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