Ek-sistence can be said only of the essence of the human being, that
is, only of the human way "to be." For as far as our experience shows,
only the human being is admitted to the destiny of ek-sistence. Therefore
ek-sistence can also never be thought of as a specific kind of living creature
among others - granted that the human being is destined to think the
essence of his being and not merely to give accounts of the nature and history
of his constitution and activities. Thus even what we attribute to the
human being as a n i d i t a r on the basis of the comparison with "beasts" is
itself grounded in the essence of ek-sistence. The human body is something
essentially  other than an animal organism. Nor is the error of biologism
overcome by adjoining a soul to the human body, a mind to the soul.
and the existentiel to the mind, and then louder than before singing the
praises of the mind - only to let everything relapse into "life-experience,"
with a warning that thinking by its inflexible concepts disrupts the flow
of life and that thought of being distorts existence. The fact that physiology
and physiological chemistry can scientifically investigate the human
being as an organism is no proof that in this organic thing, that is, in
the body scientifically explained, the essence of the human being consists.
That has as little validity as the notion that the essence of nature has been
discovered in atomic energy. It could even be that nature, in the face it
turns toward the human being's technical mastery, is simply concealing i n
essence. Just as little as the essence of the human being consists in being
an animal organism can this insufficient definition of the essence of the
human being be overcome or offset by outfiitting the human being with an
immortal soul, the power of reason, or the character of a person. In each
instance its essence is passed over, and passed over on the basis of the same
metaphysical projection.

(- martin Heidegger,  1947 )