Det förekom förr långa värme perioder, den senaste gången detta hände var för cirka 13 000 år sedan.
Kylan ersattes då av en varm och fuktig period som skulle vara i flera tusen år och stenåldersmänniskor i Sverige kunde bland annat plocka vindruvor och fånga sköldpaddor, lättast var kärrsköldpaddan att fånga då den fanns i sjöarna.
DNA mässigt (mitokondrie-DNA Haplotypes) är den Polska enklaven av kärrsköldpaddor inte densamma som den i Sverige. De skiljer sig DNA mässigt åt och till hör grupp II (a och b). Temperaturen blev för låg under sommarmånaderna (juli) för att ägg skulle kunna kläckas.
Även mjukskaliga sköldpaddor förekom på dieten när så bjöds. Havsläderskölpaddor kommer än idag ner längs västkusten in i Öresund och även ibland neråt södra delen av Östersjön, även om det är en rar händelse idag. Det står att läsa lite då och då i olika tidningar. Val förekom också i östersjön långt tillbaka.
För den nyfikne finns mycket om detta intressanta djur och om klimat källorna nedan, som tyvärr är lite för lång kanske

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