in which order did they evolve?

IIRC, Animals and Fungi are the most recent, with plants splitting off right before, protists before that, and archaea and bacteria were the first (it's unclear whether one evolved from the other and which was first).

thanks mokele. i asked this question on yahoo answers and was surprised at the confusion my question caused. hardly anyone (including graduates) seemed to know what i meant by 'kingdoms'. isn't 'kingdoms' standard taxonomy?

 

also, the one person who wasn't confused reckoned they evolved in the following order;

 

archaea; bacteria; protists; fungi; plants; animals;

 

any thoughts?

Well, "kingdoms" aren't often used anymore - we tend to refer to the three 'domains' (archaea, prokaryota, and eukaryota), which are based on cell structure, genetics, etc.

But Mokele is really really old so he knew what you meant.

First : all life is equally ancient. It appears that the first life appeared 3 to 4 billion years ago (probably nearer 4 billion) and all life since has evolved from that original form. For this reason it is a bit misleading to think of primitive and advanced forms of life, since all life is equally advanced.

 

Second : the divisions between kingdoms, once you go back in time, is not very distinct, and the fossil record is often scanty. This means that the point at which a particular kingdom first appeared is often vague. Sorry, but this means that the question cannot be answered with certitude. For example : we cannot say whether bacteria or archaeans arose first.

 

Intuitively, we would think that the order was similar to what you stated 3 posts back. However, we could easily be wrong.

IIRC the current consensus was that archaea and bacteria share a common ancestor.

To Charon

That is correct. The first 'life' was probably a self replicating molecule drifting in a solution of organic molecules, made by inorganic processes, and using the substances around it as raw material to make more molecules. Some would have become trapped in lipoprotein vesicles, making the first 'cell'.

 

From the first such successful proto-life came all that followed, including archaeans and bacteria. What a lot of people fail to understand is that even small archaeans are highly complex and sophisticated organisms, after almost 4 billion years of evolution.

no one can tell the exact order of evolution of different kingdoms but my proposed order is Archaea - Eubacteria - Plants & Protists - Fungi & Animals

 

the order is according to their complexity and habitat.

Why, do you think, are archaea less complex than bacteria?

Do not be confused by the name, it has historic reasons.

Isn't there even (limited) debate on how many Kingdoms there are?

Sure there is. I have not commented whether a distinction into six kingdoms actually makes sense or not, because afaik in most text books you will find the 5 or 6 kingdom classification. Mokele or other on this forum that deal more with taxonomy will likely be able to give more insight into this.

 

E.g. Cavalier-Smith proposed in the 90s a system in which bacteria and archaea form one kingdom again (Bacteria), and the others are Protozoa, Animalia, Fungi, Plantae and Chromista. It actually resembles somewhat earlier classfication schemes (at least superficially).