The On Line Guide to the Current State of Forerunner Research - Edition 3206

The Forerunners were an important sentient species originating about 1-3 million years ago. About 10,000 years ago they 'disappeared'.
We are fairly certain that they are highly likely to be a spacefaring species - we have evidence of their civilisation on many worlds in human space, in all quadrants. We also now have evidence of crash sites for both small craft and what we believe to be inter-planetary (if not interstellar) craft

Biology
The Forerunners were very probably hominid carbon-based possibly even DNA-based sentients. We have no complete images of their appearance - though it is very likely that they were smaller than human.
We have recently come accross what might be some funerary evidence such as bones or other remains from which to determine better their size appearance - though the low incidence is such that it is hard to draw good conclusions.

Artist's impression of what a Forerunner might have looked like

General Sociology
In no case have there ever been any finds or evidence of forerunner cities or major constructions - even given the time since their civilisation fell, some evidence would be expected. We now have significant finds of what could be termed cities - many sites are small but some extend for kilometres giving significant areas of potential finds to cover.
This has led to a number of currently unprovable conjectures - some or all of which may turn out to be correct:

1. The forerunners were exceptionally long lived - in other species generally low fertility goes with longevity.
2. The forerunners were solitary and did not group, as humans do into social cohorts - and hence did not use cities - though the discovery of large area sites mitigates against this view.
3. The forerunners deliberately removed evidence of their civilisation - there is a lot of evidence point to this - though whether archeological evidence was deliberately removed, or whether it was of a perishable nature such that it does not survive is less clear. It is also not (yet) possible to say whether it was natural for the forerunners to demolish a site before moving on and building another - in a high tech version of subsistence farming - or whether all the sites were demolished simultaneously at the time they disappeared
4. Forerunner cities were so alien that we are unable to recognise their remains as such - We have been able to identify remains areas that appear to be concentrations of activity - "cities" if you will - though it remains true that there may be many forerunner artefacts that are not yet recognised for what they are.

As a result of the recent increase in study of the forerunners, as well as a careful trawl of the archives and records from early human exploration, we have started to build a picture of the extent of Forerunner activity.

Some systems do seem to have greater than average incidences of forerunner 'finds'. Though this does tend to correlate directly with how long the search for artefacts or sites on a world has been underway; for example the vast majority of inhabited worlds in Q0 have forerunner finds (only a handful do not - or have not yet found or declared such sites) and the vast majority of them have multiple finds. Outside Q0, no world has, as yet, had multiple finds.

Seeding
The worlds suitable for human colonisation in human space all have working biospheres. There has been a theory around for some time that this might have been as a result of Forerunner terraforming efforts. We have conducted further studies into this, and have found some evidence of earlier, non-DNA based life on some worlds, almost always completely incompatible with the current life forms inhabiting the planets today. Study of the geological records have indicated that the current giant reptile species common on most worlds, may only be a few million years old - rather than the hundreds of millions of years one would have expected in the case of a freely evolved ecosystem.
There has not been time to check this out on all worlds as yet (such a survey would be a mammoth undertaking, requiring decades, if not centuries of study) - but early indicators are interesting.
This is the best evidence yet to support the Forerunner Seeding Hypothosis.

Forerunners and AI
It has been suggested that the forerunners appear to have co-existed peacefully with Moriarty-Class AI (MAI) which were integrated in Forerunner society,
However, the only evidence we have for this is the word of a single AI discovered in an abandoned base in Wood's Asteroid, Tuskan - and it was cut off from communication. Given that Moriarti AI, in human experience, lie, cheat, kill and outwit humanity at every turn, we feel that this evidence is untrustworthy in the extreme.
It is as likely as anything else that the AI on Woods Asteroid destroyed the previous occupants of Woods Asteroid itself - and was only waiting for the opportunity to escape to carry out whatever unfathomable (and probably unpleasant) acts it had been plotting for millennia. In other words, how do we know Woods Asteroid wasn't a prison? Of course, against this view one could ask why would one imprison an AI? Humanity to date has chosen to destroy rather than attempt to reprogramme or rehabilitate the rogue AI it has produced. Based on the clear technological superiority of the commonplace artefacts we find, it would be very unsound to equate either the capabilities or intentions of forerunner AI with those created heretofore by humanity

Finally - there have been some hints that there may be other functioning 'MajorDomo' AI units in human space. Searching for these has been started as a matter of high priority - though extreme caution will be exercised should any of them be located (if, indeed, they exist).

Forerunner Genetic Engineering
There has been some evidence collected that indicates that the Forerunners developed genetic engineering to levels far beyond that currently available to humanity - evidence continues to accumulate on this front - they do seem to have tinkered in areas that humanity hasn't even thought of yet

Forerunner Technologies
Based on a variety of sources, there has been a great deal of conjectural work on some Forerunner technologies, as well as close study of devices found.

Here are some of the less outlandish ideas