2024-04-11 12:34 来源：得道网
新的气候重建显示，气温和降雨下降的时期与袭击罗马帝国的三场瘟疫同时发生，布鲁斯·鲍尔在《气候驱动古代瘟疫吗?》(SN: 2/24/24，第13页)。
鲍尔报告说，研究人员不确定这些气候变化究竟是如何影响瘟疫的传播的。读者罗伯特·j·麦考恩(Robert J. MacCoun)问，一种解释是否可能是，更冷的天气迫使人们在通风不良的室内待的时间更长。
Cold periods do “tend to bring people indoors, closer together, increasing the chances of spreading infectious disease,” says classical archaeologist Brandon McDonald of the University of basel in Switzerland. But this is just one of many ways that climate shifts can impact disease spread. Identifying the pathogen behind an infectious disease is a crucial part of the puzzle, McDonald says. That’s because some changes in temperature and precipitation are advantageous to certain pathogens and the animals that spread them but disadvantageous to others.
“For most Roman period [disease] events, we haven’t yet scientifically determined the pathogenic cause,” McDonald says. While the new findings are noteworthy, he says, researchers need to know more about the diseases and their ecology to determine how climate may have influenced their spread.
A Panamanian tree fern is the first known plant that turns dead leaves into roots that seek out nutrient-rich soil, Darren Incorvaia reported in “Fern revives dead leaves” (SN: 2/24/24, p. 5).
Reader Douglas B. Quine was surprised that the discovery was considered novel, given that the leaf-into-roots process seems similar to the widespread practice of propagating plants using leaf cuttings.
The root formation observed in the fern, called Cyathea rojasiana, is a different process from propagation through leaf cuttings, says tropical forest ecologist James Dalling of the University of Illinois Urbana-Champaign. In cuttings, new roots and leaves are created in the leaf or leafstalk and differentiate into completely new leaf and root tissue. “The original leaf dies,” Dalling says. “In C. rojasiana, the original leaf loses its photosynthetic function and partially decomposes but continues to live for many years, functioning as a root. In this case, the vascular tissue of the leaf is repurposed.”
