It would be interesting to build a conlang lexicon age by age.

To begin with, certain functional words would be created like pronouns,
prepositions (and/or case endings), and whatever particles, conjunctions,
etc. would be necessary to build simple sentences.

Next, nouns and verbs relating to the most basic of biological necessities
are created: A few food terms, "water", "eat", "hunger", "defecate", ...,
and some kinship terms that would apply to a small band or an extended
family group, perhaps including such terms as "mother", "father", "son",
"daughter", "chief", etc. These would be the words used by any culture no
matter how "primitive" or "civilized".

Once those are in place, work on the nouns, verbs, and adjective/adverbs
that would be used by a nomadic band of hunter-gatherers. Names of plants,
prey animals, and dangerous predators, adjectives for hot, cold, warm, wet,
dry, light, dark, brave, afraid, and whatever activities would be typical
of such a group including hunting, gathering, food preparation, tool
making, fire making, and so on.

Certain technological advances would come along and require new vocabulary.
Spear-throwers, bow and arrow, stone spear points and arrow heads, stone
knives, fabric weaving, basket weaving, pottery, and so on.

Next might come the words relating to a more settled agricultural
existence. Domesticated animals, crop plants, verbs for tending animals,
plowing fields, harvesting, cooking, wine and beer making. All the tools
and implements would need names, as well as the plants and animals, and the
processes and procedures. Along with agriculture came more complex social
arrangements so that words related to larger-scale governance, cities,
armies, and warfare might be coined around this time.

At each stage the conlang could be evolved somewhat so that the more
"primitive" words would follow "the old ways" while more recent words might
be coined of newer materials. Built up layer by layer over an extended
period of time the conlang could take on a very naturalistic flavor.

I guess I should start with a book that gives a good overview of everyday
life in the stone age. Any ideas on how to go about arranging words
chronologically by age?