Page 220 - The Evolution Impasse 2

218 Transition from Water to Land Dilemma, The

They as sume that these bones grad -
u al ly de vel oped in to weight-bear ing
feet. Yet un like the feet of land Capsule
-Cortex
dwell ers, the bones in a fish's fins are
Medula
not con nect ed di rect ly to their back - Renal ar -
bone. This means they can not per - tery
form a weight- bear ing func tion, as
do the leg bones in ter res tri al an i -
mals. Therefore, the claim that these
Renal vein
fins slow ly evolved in to feet is Renal pel -
ground less. vis
Ureter
2) Heat pro tec tion: On land, tem -
per a tures can change very fast and
with in a wide range. A ter res tri al an -
i mal's me tab o lism al lows it to adapt
to these tem per a ture chan ges in. In
The Kidney Barrier
the sea, how e ver, tem per a tures
Fish re lease harm ful by prod ucts in their bod -
change very slow ly, and do not ies di rect ly in to the wa ter. Terrestrial an i mals,
range as wide ly as on land. A crea - how e ver, need kid neys. Therefore, any an i mal
that makes the tran si tion from wa ter to land
ture ac cus tomed to the sea's even
re quires kid neys be fore mak ing the change.
tem per a tures there fore needs to ac -
However, kid neys have a high ly com plex
quire a pro tec tive sys tem ap pro pri - struc ture. Moreover, a kid ney has to be ful ly
ate to the tem per a ture swings on formed and flaw less if it is to func tion. Only
50%, or 70% or even 90% of a kid ney will
land. It would be ri dic u lous to claim
serve no pur pose. Since the the o ry of ev o lu -
that fish ac quired such a sys tem
tion is pred i cat ed on the idea that or gans that
through ran dom mu ta tions as soon are not used dis ap pear over time, a kid ney
as they emerged on to dry land. that is 50% lack ing will be elim i nat ed from
the body at the first sta ges of ev o lu tion.
3) Use of wa ter: Water is an es sen -
tial re quire ment for liv ing things,
thirst when they need wa ter. Yet un -
and on land, its avail a bil i ty is lim it -
der wa ter crea tures have no sense of
ed. For that rea son wa ter, and even
thirst and their skins are not suit ed
mois ture, must be used eco nom i cal -
to a dry en vi ron ment.
ly. For ex am ple, skin must pre vent
4) Kidneys: Due to the abun dant
wa ter loss and evap o ra tion, and
wa ter in their en vi ron ment, ma rine
land dwell ers must be able to feel

The Evolution Impasse II