On reflection, I think that teleology must be of the nature of following a blueprint plus instructions - in other words, teleology entails achieving what is already in existence conceptually.
And therefore teleology is not a matter of following a particular direction towards some as-yet unrealized condition. In other words, with teleology, the destination must be foreknown - you have to know where you are going.
This means that in a teleological, purposive concept of evolution on earth; the perceptible evolutionary sequence must be conceptualized as a process of incremental - step-by-step - development towards a situation which already exists as a plan.
Indeed, this must be the case if things are to be coordinated - the coordination of nature, of reality, must be 'top-down' - so that things evolve to occupy pre-ordained 'slots'.
(This is not to deny that other types of evolution are working against this plan - for example entropic change and natural selection.)
The unifying purpose - to make more Deities from Men
The primary purpose of evolution is to make more Deities - the highest type of consciousness, this is achieved by the deification of Men - so the intermediate purpose is to make Men - which is done via raising animal consciousness, which is done by raising plant consciousness, which is the first obvious form of 'life' itself derived from the primordial level of the simplest and minimal level of baseline life and consciousness which is found in the mineral, physical world (a world that is usually assumed to be non-living and non-conscious).
1. First half of evolution: Creating the plan
So, the evolutionary history of life on earth comes in two halves - the evolution of the plan then the realization of the plan; but the first half is usually neglected.
The plan evolves into a hierarchy from the simple unity of purpose at the top ('deity'), and down through layers of higher 'governing entities' concerned with advanced consciousness ('angels'), middle entities concerned with animal and plant life ('nature spirits'), and mineral entities concerned with the basic organization of matter in terms of what we would term physics and chemistry - elementary particles, fundamental forces, elements, molecules etc.
So - top-down, simplified, and descending in a pyramidal fashion, with greater numbers of simpler and more specialized governing entities at each lower level:
3. Animal then Plant Nature Spirits
4. Physical spirits
These entities are all purposive, conscious and cognitive - that is, they are capable of thought, analysis, modelling - but at very different levels. The idea is that there are extremely large numbers of extremely simple physical entities; and many-fold fewer numbers of (say) angels having far greater levels of consciousness and cognitive ability.
The first half of evolution involves the development of these purposive entities from the top downwards - until before the physical realization of creation has begun, the above hierarhcy of entities is already in place.
So this is the plan - containing both the 'blueprint' of the end result, and the step-by-step 'instructions' of how to achieve it.
2. Second half of evolution: implementing the plan
The assumption is that such a vast and complex plan cannot be implemented in one step - but requires multiple incremental steps - because only so much, some finite degree of organization, can be attained in a single step.
Therefore, at each stage the process requires the building-blocks to be ready - pre-prepared. So the first stage is to make the most primary building blocks and elaborate them stepwise until they are suitable to make first plant, then animal life of increasing complexity and consciousness; sexual reproduction, animal society; then Men - and then to raise the consciousness of Men towards Deity.
The history and sequence of evolution of and on earth is therefore the reverse direction from that of the governing entities:
4. The basic stuff and forces of the universe - The universe, solar system, earth; the physico-chemical 'mineral' structures of earth - done by Physical Spirits
3. The origins of life, elaboration of life through plants and animals via specialization and coordination and sexual selection - done by Nature Spirits
2. Origins of Man - done by Angels
1. Deification of Man - done by God
The second half of evolution is - overall - therefore a process akin to (but vastly more complex and long-lasting than) the development of the fertilized egg into an organism; in the sense that it is a growth and unfolding by multiple stages towards a previously established and planned end-point.
And each and all of the major stages, as well as the integration of the whole plan, are guided by governing entities.
Conclusion: To put the whole matter extremely simply: the structure of creation is first established as a plan by the hierarchical structure of governing entities which evolve from the top downwards getting simpler and simpler as they descend; then secondly creation is organized by these governing entities from the bottom upwards, from simplest to most complex, such that the pattern of actual creation is mapped-onto the pattern of the governing entities in the reverse direction from the formation of the governing entities.
In a teleological (purposive) model of evolution I have inferred that there must be governing entities that shape evolution in order to overcome the destructive effects of entropy and short-termist and ultra-selfish natural selection, in order to enable long-term survival and reproduction to be pursued.
In general, teleology seems to be required for the imposition of a background level of cooperation and coordination between similar entities and across the different levels of organization.
If this is accepted, and some kind of general mechanism for teleology is devised - such as the hierarchy of governing entities - then the question arises as to how teleology is imposed?
There seem to be two possibilities - purpose could be imposed from outside by the operation of some kind of field, force or form; or purpose could be built-in.
While I think it likely that external forms/ fields/ forms have a role - they strike me as radically too simple, too lacking in dynamic complexity, to perform the necessary job in biological entities - although perhaps they suffice for the mineral world such as atoms, molecules, crystals etc.
My instinct is that purpose is most likely to be built in, specifically that, as an entity is formed, its purposive nature is built into the structure and organization (by the action of its governing entity) such that there is a degree of agency and self-regulation directed at the overall purpose.
For example, in multicellular organisms there may be the mechanisms of cell-suicide or apoptosis - such that if a cell experiences a mutation that may endanger the organism - perhaps by a neoplasm such as cancer - then the cell destroys itself (for the good of the whole organism).
There is considerable altruism built-in at the cellular level - white blood cells (some of which closely resemble free living amoebae) will kill themselves in the process of defending the organism against microorganism invasion (these dead soldiers are found in pus): this purpose is apparently built-into them.
Another example is reproductive self-suppression; which is found in some social animals. For instance, when a male orangutan fails to become the alpha, he remains as a partly developed adolescent. Now, in one sense he is biding his time and hoping for sneaky coercive sex with a female - but in another sense he is preserving the cohesion of the group by removing himself from competition.
Similar behaviours are seen in primates in relation to submission - a defeated male will submit and accept the dominant male - on the other side the dominant male will refrain from killing the defeated opponent.
In humans, there is considerable altruism and risk taking among young men in defending their group. Of course, this behaviour - once established, may be sustained by the advantage of protecting genetic relatives - but the behaviour had to occur and be stable before such advantage could be established; and it is consistent with observation that such motivations are built-in.
The primary reliance upon built-in teleology also makes it easy to understand the existence, indeed often at high rates, or the opposite - of behaviours which are non-functional, free-riding, parasitic. The teleology - including traits that are long-termist, altruistic, cooperative and coordinated - are vulnerable to subsequent, later events that disrupt or destroy these built-in mechanisms: such as damage or mutations during the life of the entity - mutant mitochondria in a eukaryotic cell, cancer in a multicellular organism, the effects of mental illness in human society.
Therefore, I think it most likely that governing entities work to impose teleology at the point where entities are being formed - either originally and/ or when being reproduced. The teleological behaviours are part of the design specification built into the entity.