studied the bones in more detail, it became apparent that a comparison
with tapirs was more appropriate. Tapirs live in forests, but do like to
be in the water when they have access to it: to cool off, eat water plants,
and take refuge. Pakicetids were able to get around on land and in water
too, but probably spent most of their time in freshwater ponds and riv-
ers. Their anatomy reveals more aquatic adaptations than that of a tapir
skeleton, and, just like tapirs, they were probably mostly waders.
All pakicetid fossils from Pakistan have been found in rocks that
formed in shallow ponds, in a dry climate with occasional flash floods,
as discussed in chapter 3. It is likely that these cetaceans lived like croco-
diles, hunting by sitting still in the water, waiting for unsuspecting land
animals to come and drink, or attempting to catch fish in the shallows.
Pakicetids are rare at other localities in the Kala Chitta Hills. Those
localities do have fossils of the land mammals that lived here, such as
the small artiodactyl Khirtharia, brontotheres (cow-sized and rhino-like
animals), small carnivores, and anthracobunids. All of them could be
potential prey for pakicetids, as is suggested by stable-isotope evidence.20
september 11, 2001
We published21 our Pakicetus skeletons from Pakistan less than two
weeks after the terror attacks of September 11, 2001. Soon thereafter,
the eyes of the world focused on Pakistan and Afghanistan. It became
more difficult to travel by plane in general, and specifically to work in
Pakistan, and the last time I went there was 2002. Many people in the
West began seeing that country as failed and lawless and inhabited by
savages. Pakistan has failed in some regards, and there are lawless areas
ruled by gangs of criminal bullies. However, they are not representative
of all of Pakistan. In fact, some of the greatest acts of kindness and
unselfishness bestowed on me have been by Pakistanis who had nothing
to gain from doing so and could easily have gotten themselves in trouble
for helping me.
One that I remember vividly occurred when Ellen and I flew from
Cleveland to John F. Kennedy airport in New York on an American car-
rier and then on to Islamabad on Pakistan International Airlines (PIA).
Our plane to JFK was very late, and the luggage was not checked
through. We changed terminals with carry-ons and two suitcases of gear
each. As we walked up to the check-in counter, groaning and sweating
under our heavy load, four Pakistani-looking PIA officials were chat-
The River Whales | 155
ting, but the lights at the counter had been turned off. I asked the man
behind the counter about the flight, and he said we were too late, point-
ing at the computer system—it was shut down—and he shrugged his
shoulders apologetically. My face must have dropped, but then an older
PIA man stepped in, and said, in strongly accented English: “Can you
carry all that baggage through security?”
I said yes. He said something in a language that I did not understand
to one of the others, who hurried off, and then something to the PIA
woman, who talked into her walkie-talkie. I could just understand her
Urdu words for “two” and “four.”
“Good, follow this lady,” he said.
She rushed us through security, down the terminal, to the gate. Our
four suitcases were taken from us in the jetway; they closed the plane’s
door right after we entered, and the plane left with a slight delay. Tradi-
tional Pakistani hospitality and generosity—thank you, PIA.
Chapter 12
Whales Conquer the World
a molecular sine
Tokyo, Japan, February, 2000. I think about the relatives of whales as
I travel on a metro train to visit the laboratory of Professor Norihiro
Okada. He goes by the nickname Nori, which is also the Japanese word
for a much-eaten kind of seaweed, as he points out with a broad grin.
Nori is not a paleontologist but a molecular biologist. The molecular
similarities between whales and hippos are piling up as more genes are
studied, and Nori is a central person investigating this. In his lab, dozens
of busy young people produce reams of DNA data. The DNA molecule
is like a string with four types of beads, the nucleic acids, and Nori’s lab
spends its time determining the order in which the beads occur. Animals
that are more closely related will have more similar bead-sequences
than those that are more distantly related because there was less time
for the beads to change (mutations to occur) and the sequence of strings
to diverge. Nori’s lab studies a special kind of DNA: short interspersed
nuclear elements, or SINEs.
I meet Nori in a tiny office which he shares with two secretaries. Nori
wants all his space to go to production—his labs—he does not want a
big private office. He sits on his mini-desk, barely large enough for a
computer, and I am on a tiny couch, unable to stretch my legs because
the tiny coffee table is too close. There is constant Japanese chatter from
the secretaries behind the bookshelf that partly divides the room, and
157
158 | Chapter 12
they bring us green tea. I do not like green tea, and this kind reminds me
of water that was used to boil spinach in. I add a lot of sugar to mask
the flavor.
Unlike many of his countrymen, Nori’s English is well pronounced
and articulated, although he often has to stop to think of a word, and
plurals and articles are rare.
“SINE method is very useful method. Insertion of SINE is unique
event.”
“So, tell me how SINEs end up in the genome of an animal—how are
they inserted?”
“Ahh… SINE are retroposon. SINE is very common, in humans 11
percent of genome is SINE.” I think the gasp was at my ignorance, but
he appears willing to educate this humble fossil guy nonetheless. It
emboldens me, and I seize the opportunity to learn. His answer did not
answer my question in a way I understand, so I try again.
“What is a retroposon?”
“Ahh… retroposon was inserted in host genome, maybe by help of
&
nbsp; virus element called a LINE.”
I do not know what a LINE is, but this still clears matters up some. I
know about viruses. Initially, a fragment of genetic material may have
been part of the genome of a virus. When a virus infects the cell of a
mammal, it injects its genetic material into the host cell; there it is incor-
porated into the DNA of the mammal. The mammal cell keeps on divid-
ing, and, inadvertently, also duplicates the virus DNA. That allows the
virus to take over the reproductive equipment of its host cell and make
a new virus. Some of those inserted parts are SINEs—pieces of DNA
that were initially part of the virus and not part of the DNA of the
mammals’ ancestor.
“So the host cell cannot recognize these SINEs and has no way to get
rid of them?”
“There is no known mechanism to delete SINE.” I can see that that
would be useful to determine ancestry. If some little ribbon of DNA, a
SINE, is inserted in the ancestor of an animal and can never be deleted,
it would be present in all of its descendants, and thus would be a great
marker to determine relationship between its descendants, since animals
descended from a different ancestor will not have that ribbon of DNA.
“Is it not possible that a SINE is inserted in the genome of two differ-
ent mammals independently? How do you know that a SINE that you
find in the DNA of two animals is not the result of two separate inser-
tion events in their ancestors?”
Whales Conquer the World | 159
“SINE insertion in genome is not site-specific. We determine flanking
sequences. These have to be same in case they are part of same insertion
event. Probability that insertion of SINE is in same region of different
hosts is close to zero.”
This makes sense. If some viral SINE DNA is inserted into the genome
of a host, it could end up anywhere in that genome. The chance that the
same SINE is inserted into the same stretch of DNA of a host independ-
ently in two species is very low. I ponder the implications. If what he
says is true, then this is a great way to figure out relationships. The SINE
sequence can be inserted anywhere among the millions of genes of the
host, and does not affect the function of the cell it is in. If there is no
known mechanism that allows cells to cut out these inserted SINEs, and
if they are neither harmful nor beneficial to the host, selection does
not act on them. They just sit there and are copied, generation after
generation.
That gives molecular biologists a great tool to figure out who is related
to whom. As it turns out now, hippos have a SINE in common with
whales, and it is found in the same place in the genome of the two groups.1
SINEs in common between hippos and cetaceans imply that they were
inserted into the genome of the common ancestor of those animals, but
not into an earlier ancestor that was also ancestral to cows and pigs, since
they do not have that SINE. That implies that hippos and whales are
more closely related to each other than either is to cows and pigs.
Working with Nori makes me accept that the molecular evidence
linking hippos and whales overwhelms dissenting fossil evidence to the
contrary. But it also makes me see more clearly what role the fossils still
have to play. The biggest problem with thinking of hippos as close rela-
tives of whales is that the oldest hippos are only about twenty million
years old,2 nearly thirty million years younger than the oldest whales,
and that, body-wise, the similarities are very limited. The long ghost
lineage of hippos, between forty-nine and twenty million years ago,
implies to me that the ancestors of hippos were so unlike modern hip-
pos that we do not recognize them, so we really do not know what that
last common ancestor looked like. Personally, I feel that we need to look
for something that lived around the time of the earliest whales, close to
the common ancestor of whales and hippos. But not in Kutch—the
rocks there are marine, and they are too young. I have to explore other
places. The older rocks in Pakistan are now unsafe to go to—maybe
places where I have never been in the Indian Himalayas. I make a men-
tal note to that effect.
160 | Chapter 12
the black whale
It will take time to start elsewhere, and Kutch is still producing interest-
ing fossils. I consider how sad it will be to stop working in Kutch as we
drive through its desert to the locality Dhedidi North. Forty-one million
years ago, Dhedidi North was a lagoon that was slowly drying out (fig-
ure 30). There are some cool fossils here—a snake skull larger than my
hand and a crocodile snout longer than my leg. Based on those, it must
have been a scary place to walk around in back then. All these beasts
perished the same way: their death came as they were trapped in the hot
mud that slowly dried out and they were baked inside as their lagoon
dried up. Many of them became ugly fossils, because gypsum dissolved
in the water precipitated upon evaporation and formed a crust around
the bones and teeth. Crystals also grew in the little cavities inside the
bones and cracked and split the bones open.
The place is more pleasant in modern times. We park our car on the
high yellow ledge, the Fulra Formation (Fulra Limestone, figure 28),
and walk down into the gypsified mudstones of the Harudi Formation
on one of the many trails made by roaming cattle. The nearby village of
Dhedidi is traditionally inhabited by milkmen. Milkmen here do not
buy and resell their milk; instead, they have their own herds of bovine
producers, and those graze on the sparse grass around me. In the morn-
ing, the milkmen ride off on bicycles or motorcycles, metal jugs dan-
gling from their handle bars and luggage racks, to peddle milk door to
door in the villages.
Much of the fossil bone here is black, and the colors of the rock vary
from ochre red to yellow and brown, plus bright-white gypsum, distrib-
uted in no particular pattern. The gypsum crystals grow in regular
shapes that are suggestive of the regular shapes that fossils have, and I
pick up many piece
s of presumed fossils that on closer inspection disap-
point. As I climb down a low hill, a row of five shapes the size of oranges
attracts my eye. When I kneel down, they turn out to be vertebrae,
arranged just as they were when they were still in the animal, millions
of years ago. Usually this would be very exciting, suggestive that much
more of this animal was buried, but these particular ones do not enthrall
me because they are in terrible shape. Gypsum surrounds them on all
sides, and they are weathered into jagged shapes. It is as if someone with
a bone-cutting knife randomly hacked at them. I can just recognize
them as rib-bearing thoracic vertebrae, and, sure enough, scattered
around them are pieces of ribs and other vertebrae. The ribs are not
Whales Conquer the World | 161
pachyostotic. This was a fossil whale. I gather the loose-lying fragments
in piles and then dig in the place where the quintuplets protrude from
the hill.
On one side, there clearly is nothing. Weathering has excavated it for
me, decades or centuries ago, and pulverized what it found. On the
other side, the sediment is not eroded, and I run almost immediately
into another vertebra as I start to dig. This vertebra is much better pre-
served—black and with just a bit of gypsum, but also with several of its
processes intact. The fossils are fragile, and it requires a number of
cycles of brushing out dirt, gluing cracks, letting glue dry, and exposing
more of the fossil. A second vertebra is located immediately behind it,
and this one is articulated with the first. Both are partly gypsum-
encrusted, and that slows down the process of excavation. The two col-
lectors with me have noticed that I have not moved for a while, an
indication to them that I found something. They come over to help. We
remove the overburden and excavate further, finding more vertebrae.
The row of vertebrae snakes around into the muddy knoll I’m sitting
The Walking Whales Page 24