Alteration of the Generations

Flowering plants give birth to their grandkids,
Two generations on.
Between them, a haploid stage in birthed,
And breeds, and dies in a matter of hours.
It’s evolution at play, and history,
Old ways still acting upon –
The hidden generation,
That is lurking deep within the bowers.

The parent cells, barely ten in total,
Died at the point of conception –
But isn’t the same as true in animals ?
Well, yes…and no.
The thing is, they have further stripped their gametes down
To uni-perfection –
No longer build a multicellular form,
They have no need to grow.

But mosses and ferns, they still do it old school –
Separate independent stages –
And algae can even be free-living –
Single, double, single, double…
So botanists have marvelled,
And have filled their textbook pages –
But have drawn the line at animals,
To spare them family trouble.

Yet I suppose there’s one more diff’rence –
If the egg and sperm that made me
Were my parents…well, that means,
My parents are within me to this day –
They gave their lives, and gave their haploid matter
To upgrade me –
So my generation has it easy,
Born with twice the DNA.

Botanists like to point out how the ancestral condition of alternating between haploid (one set of chromosomes) and diploid (two sets) each generation still exists in flowering plants, but in a very reduced form.  And it is true that pollen contains two-to-three cells, and the ovule seven, making them both technically multicellular.

And yet zoologists never seem to mention that the same is true for animals, only here the haploid generation has been reduced even further – now both gametes are single-celled, and their entire mass is consumed by the emergent zygote rather than withering away like all of the haploid plant material bar the two nucleuses.  I guess they’ve got to draw the arbitrary line somewhere…