Refuting Evolution

[The Grand Nudger]

Living cells, yes,

It's a little more precise than that, just to give you a pro-tip

would you like to explain in your own words at what point the ancestor of both humans and bananas existed?

Eukaryota, approx 1.6 billion years ago

What type of cells were formed that differentiated the two?

The basic cellular structure of life is much, much older and common to all life. The cell, is a very successful structure (the pro-tip above rears it's ugly head). Amusingly, different types of genes provide similar functions in dissimilar ways. For example, HOX in animalia puts a tail on one end and a head on another - whereas in plantae MADS box puts flowers on one end and roots on another. Animalia has MADS box - but doesn't use them to form patterns, whereas plantae has HOX - but doesn't use them to form patterns.

As opposed to the above, we see similarity, in that chromotin process is maintained between members of the two groups (in some cases with homologous structures after pattern formation -CLF in Arabidopsis/E(z) in flies).

Back to differences- cell signaling in the two groups is handled by different receptors (animals have receptors and signalling processes that plants do not possess-at all), and at the same time plants are capable of much greater horizontal transfer than animals (chloroplasts are an example of this sort of transfer which clearly occurs in plantae -via cynobacteria - but not animalia).

To sum it all up, that a common ancestry is apparent in these two groups is established both by homologous genetic structures and processes - and by what we understand of heredity ( common genetic material comes from -someplace- and the only someplace we're aware of is a common ancestor). What differentiates these two groups is not necessarily what they are composed -of- (as noted, the difference in composition between bananas and human beings is not so vast as some would imagine) - but how that composition is -arranged- (MADS box/HOX), and how it's components interact with each other(cell signaling/horizontal transfer).

The LCA of animalia and plantae was almost certainly a single celled organism (which rules some eukaryota out-but it must be eukaryota as far as we can determine), but beyond that point, development of structures was completely independent - even though the structures which arose from this development are often exceedingly similar.