1. Presented
by
islam jan buneri
presented
to
dear sir sharoz khan lecturer at awkum buner

2. Recapitulation theory
• The theory of recapitulation, also called the biogenetic
law or embryological parallelism, proposed by Ernst Haeckel's

3. • Haeckel formulated his theory as "Ontogeny recapitulates
phylogeny".
• The notion later became simply known as the recapitulation theory.
• Ontogeny is the growth (size change) and development (shape
change) of an individual organism; phylogeny is
the evolutionary history of a species.

4. For example, Haeckel proposed that the pharyngeal grooves between
the pharyngeal arches in the neck of the human embryo not only
roughly resembled gill slits of fish, but directly represented an adult
"fishlike" developmental stage, signifying a fishlike ancestor.
• Hackle represent that human evolved from fish like ancesters

5. Haeckel produced several embryo drawings that there are
similarities between embryos of related species. The misinformation
was propagated through many biology textbooks, and popular
knowledge, even today. Modern biology rejects the literal and
universal form of Haeckel's theory.

6. • Darwin's view, that early embryonic stages are similar to the
same embryonic stage of related species but not to the adult
stages of these species, has been confirmed by
modern evolutionary developmental biology

7. Rejection
Today, scientists think that Haeckel overstated the
case.
For example,
1)the "gills" of a developing human do not work
as the gills of fishes as hackel said .

8. 2)It was discovered that developing babies don't look exactly like
the pictures Haeckel drew.
3)Haekel's discussion was entirely about morphology: he did not
discuss the evolution and development of animal behaviour

9. 1)Before they are born, developing organisms of different species look
similar.
2)This similarity lasts longer in species which split from each other
rather recently.
Modern observations

10. • 3)Before they are born, developing organisms may
have traits which they do not have when born, but which the
organisms that they evolved from had when they were adults.