What was done
The authors studied changes in diatom assemblages preserved in a sediment core extracted from Pilkington Bay, Lake Victoria, East Africa, together with diatom and pollen data acquired from two nearby sites.

What was learned
The three coherent data sets, in the words of the authors, revealed a "roughly 1400- to 1500-year spacing of century-scale P:E [precipitation:evaporation] fluctuations at Lake Victoria," which they say "may be related to a ca. 1470-year periodicity in northern marine and ice core records that has been linked to solar variability (Bond et al., 1997; Mayewski et al., 1997)."

What it means
These results attest to the widespread occurrence of the non-CO2-induced millennial-scale oscillation of climate that reverberates through ice age and interglacial alike, manifesting itself primarily through significant warmings and coolings in some regions and by significant changes in moisture availability in other locations, but in all times and places owing its existence to cyclical variations in some form of solar activity.

References
Bond, G., Showers, W., Chezebiet, M., Lotti, R., Almasi, P., deMenocal, P., Priore, P., Cullen, H., Hajdas, I. and Bonani, G.  1997.  A pervasive millennial scale cycle in North-Atlantic Holocene and glacial climates.  Science 278: 1257-1266.

Mayewski, P.A., Meeker, L.D., Twickler, M.S., Whitlow, S., Yang, Q., Lyons, W.B. and Prentice, M.  1997.  Major features and forcing of high-latitude northern hemisphere atmospheric circulation using a 110,000-year-long glaciochemical series.  Journal of Geophysical Research 102: 26,345-26,366.