Standards of evidence and Paleoindian demographics

Northern peatland initiation lagged abrupt increases in deglacial atmospheric CH 4

“…Although many other studies have employed summed calibrated probability distributions to summarize 14 C date compilations (e.g., 19-21), we are mindful that there are limitations and pitfalls to this approach (22)(23)(24). For example, 14 C dates with large laboratory uncertainty terms typically result in wide calibrated age ranges that can blur peaks and troughs in summed probability curves.…”

Chronological evidence fails to support claim of an isochronous widespread layer of cosmic impact indicators dated to 12,800 years ago

“…34, p. 2531).We even relaxed one of their criteria, namely that "only 14 C dates with measurement precisions <100 years, and preferably <60 years, should be used" in assessing the supposed impact chronology and its potential effects (69). Had we applied it, we would have had to discard all luminescence ages and almost 60% of all radiocarbon ages used by YDIH proponents.…”

Is it agriculture yet? Intensified maize-use at 1000 cal BC in the Soconusco and Mesoamerica

“…Identified maize kernels were preferentially targeted to confirm the associations between temporally diagnostic ceramic assemblages and the carbonized maize remains, but also to avoid the old wood problem (e.g., Schiffer, 1986;Kennett et al, 2002). Carbonized maize remains and other ecofacts (e.g., purified animal bone collagen; Kennett et al, 2008) are short-lived organisms and have a greater probability of accurately dating the depositional events of interest and, in this case, changes in the density of maize remains through time. Indeed, we AMS 14 C dated one wood charcoal sample because of the absence of suitable short-lived materials in one critical sample and it returned a date far too late (UCIAMS-57031; 895-815 BC, 2r) to be associated with the Cherla phase ceramics with which it occurred (1400-1300 cal BC).…”